Foldable display device

ABSTRACT

A foldable display device including a lower module having a first side end disposed in a first side area of the foldable display device; a display module including: a main region including a display area and a first side end disposed in the first side area; a sub region disposed under the lower module, overlapping the main region, and having a first side end disposed in the first side area; and a bent region disposed between the first side ends of the main region and the sub region and having an outer surface between an upper surface of the main region and a lower surface of the sub region, and an inner surface between a lower surface of the main region and an upper surface of the sub region; and a functional module and a window module each having a first side end disposed in the first side area.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/387,489, filed on Apr. 17, 2019, which claims priority from and thebenefit of Korean Patent Application No. 10-2018-0051804, filed on May4, 2018, each of which is hereby incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND Field

Exemplary embodiments of the invention relate generally to a displaydevice and, more specifically, to a foldable display device that canswitch between a folded state and an unfolded state.

Discussion of the Background

Display devices may display images and include a display panel, such asan organic light-emitting display panel or a liquid-crystal displaypanel.

For example, a mobile electronic device includes a display device forproviding an image to a user. More and more mobile electronic devicesinclude a display screen that is relatively larger in size than aconventional display screen while having the same or smaller volume orthickness. Also, a foldable display device or a bendable display devicethat can be folded and unfolded to provide a larger screen only at thetime of the usage is being developed.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Devices constructed according to exemplary embodiments of the inventionare capable of providing a foldable display device with improved qualityand a method of fabricating the same.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

Example embodiments are directed to a foldable display device. Thefoldable display device may include a lower module, a double-sidedadhesive layer, a display module, a functional module, and a windowmodule. The lower module may have a first side end S-4 d disposed in afirst side area of the foldable display device. The double-sidedadhesive layer may be on the lower module. The display module may be onthe double-sided adhesive layer. The display module may include, as onebody, a main region, a sub region, and a bent region. The main regionmay include a display area disposed over the lower module. The mainregion may have a first side end S-MR disposed in the first side area.The display area may include an emissive unit having a first electrode,a second electrode, and an emission layer between the first and secondelectrodes. The display area may have a first side end S-DPA disposed inthe first side area. The sub region may be disposed under the lowermodule. The sub region may overlap the main region. The sub region mayhave a first side end S-SR disposed in the first side area. The bentregion may be disposed in the first side area. The bend region may bedisposed between the first side end S-MR of the main region and thefirst side end S-SR of the sub region such that the bent region is bentbetween the first side end S-MR of the main region and the first sideend S-SR of the sub region. The bent region may have an outer surfacebetween an upper surface of the main region and a lower surface of thesub region, and an inner surface between a lower surface of the mainregion and an upper surface of the sub region. The functional module maybe disposed on the main region. The functional module may have a firstside end S-2 d disposed in the first side area. The window module may bedisposed on the functional module. The window module may have a firstside end S-3 d disposed in the first side area. The display module mayinclude a lower inorganic encapsulation structure and an upperencapsulation structure. The emissive unit may be located between thelower inorganic encapsulation structure and the upper encapsulationstructure. Both of the upper encapsulation structure and the windowmodule may be flexible. The first side end S-MR of the main region maybe disposed outwardly away from the first side end S-DPA of the displayarea in plan view. The first side end S-MR of the main region may not bedisposed inwardly away from the first side end S-4 d of the lower modulein plan view. The upper encapsulation structure may have a lower surfacecomprising only at least one inorganic material. The lower inorganicencapsulation structure and the upper encapsulation structure maydirectly contact each other to encapsulate the emissive unit. Thefoldable display device may comprise a height-compensating layerstructure having at least a portion disposed on the main region,disposed outwardly away from the first side end S-2 d of the functionalmodule in plan view, and disposed inwardly away from the first side endS-MR of the main region in plan view. The height-compensating layerstructure may have, between the main region and the window module, aheight substantially the same as a distance between the main region andthe window module. The height-compensating layer structure may supportthe window module, which is flexible, to prevent the window module frombending. The height-compensating layer structure may prevent anaccumulation of contaminants near the first side end S-2 d of thefunctional module.

Example embodiments are directed to a foldable display device. Thefoldable display device may a lower module, a double-sided adhesivelayer, a display module, a functional module, and a window module. Thelower module may have a first side end S-4 d disposed in a first sidearea of the foldable display device. The double-sided adhesive layer maybe on the lower module. The display module may be on the double-sidedadhesive layer. The display module may include, as one body, a mainregion, a sub region, and a bent region. The main region may include adisplay area disposed over the lower module. The main region may have afirst side end S-MR disposed in the first side area. The display areamay include an emissive unit having a first electrode, a secondelectrode, and an emission layer between the first and secondelectrodes. The display area may have a first side end S-DPA disposed inthe first side area. The sub region may be disposed under the lowermodule. The sub region may overlap the main region. The sub region mayhave a first side end S-SR disposed in the first side area. The bentregion may be disposed in the first side area. The bent region may belocated between the first side end S-MR of the main region and the firstside end S-SR of the sub region such that the bent region is bentbetween the first side end S-MR of the main region and the first sideend S-SR of the sub region. The bent region may have an outer surfacebetween an upper surface of the main region and a lower surface of thesub region. The bent region may have an inner surface between a lowersurface of the main region and an upper surface of the sub region. Thefunctional module may be disposed on the main region. The functionalmodule may have a first side end S-2 d disposed in the first side area.The window module may be disposed on the functional module. The windowmodule may have a first side end S-3 d disposed in the first side area.The display module may include a lower inorganic encapsulation structureand an upper encapsulation structure. The emissive unit may be locatedbetween the lower inorganic encapsulation structure and the upperencapsulation structure. Both of the upper encapsulation structure andthe window module may be flexible. The first side end S-MR of the mainregion may be disposed outwardly away from the first side end S-DPA ofthe display area in plan view. The first side end S-MR of the mainregion may be not disposed inwardly away from the first side end S-4 dof the lower module in plan view. The upper encapsulation structure mayhave a lower surface comprising only at least one inorganic material.The lower inorganic encapsulation structure and the upper encapsulationstructure may directly contact each other to encapsulate the emissiveunit. The foldable display device may comprise a height-compensatinglayer structure having at least a portion disposed on the main region,disposed outwardly away from the first side end S-2 d of the functionalmodule in plan view, and disposed inwardly away from the first side endS-MR of the main region in plan view. The height-compensating layerstructure may have, between the main region and the window module, aheight substantially the same as a distance between the main region andthe window module. The height-compensating layer structure may supportthe window module, which is flexible, to prevent the window module frombending. The height-compensating layer structure may prevent anaccumulation of contaminants near the first side end S-2 d of thefunctional module. The foldable display device may comprise a bendingprotection layer disposed on the outer surface of the bent region. Thebending protection layer may a first portion included in the at leastthe portion of the height-compensating layer structure. The firstportion of the bending protection layer may contact the first side endS-2 d of the functional module.

Example embodiments are directed to a foldable display device. Thefoldable display device may a lower module, a double-sided adhesivelayer, a display module, a functional module, and a window module. Thelower module may have a first side end S-4 d disposed in a first sidearea of the foldable display device. The double-sided adhesive layer maybe on the lower module. The display module may be on the double-sidedadhesive layer. The display module may include, as one body, a mainregion, a sub region, and a bent region. The main region may include adisplay area disposed over the lower module. The main region may have afirst side end S-MR disposed in the first side area. The display areamay include an emissive unit having a first electrode, a secondelectrode, and an emission layer between the first and secondelectrodes. The display area may have a first side end S-DPA disposed inthe first side area. The sub region may be disposed under the lowermodule. The sub region may overlap the main region. The sub region mayhave a first side end S-SR disposed in the first side area. The bentregion may be disposed in the first side area. The bent region may belocated between the first side end S-MR of the main region and the firstside end S-SR of the sub region such that the bent region is bentbetween the first side end S-MR of the main region and the first sideend S-SR of the sub region. The bent region may have an outer surfacebetween an upper surface of the main region and a lower surface of thesub region. The bent region may have an inner surface between a lowersurface of the main region and an upper surface of the sub region. Thefunctional module may be disposed on the main region. The functionalmodule may have a first side end S-2 d disposed in the first side area.The window module may be disposed on the functional module. The windowmodule may have a first side end S-3 d disposed in the first side area.The display module may include a lower inorganic encapsulation structureand an upper encapsulation structure. The emissive unit may be locatedbetween the lower inorganic encapsulation structure and the upperencapsulation structure. Both of the upper encapsulation structure andthe window module may be flexible. The first side end S-MR of the mainregion may be disposed outwardly away from the first side end S-DPA ofthe display area in plan view. The first side end S-MR of the mainregion may be not disposed inwardly away from the first side end S-4 dof the lower module in plan view. The upper encapsulation structure mayhave a lower surface comprising only at least one inorganic material.The lower inorganic encapsulation structure and the upper encapsulationstructure may directly contact each other to encapsulate the emissiveunit. The foldable display device may comprise a height-compensatinglayer structure having at least a portion disposed on the main region,disposed outwardly away from the first side end S-2 d of the functionalmodule in plan view, and disposed inwardly away from the first side endS-MR of the main region in plan view. The height-compensating layerstructure may have, between the main region and the window module, aheight substantially the same as a distance between the main region andthe window module. The height-compensating layer structure may supportthe window module, which is flexible, to prevent the window module frombending. The height-compensating layer structure may prevent anaccumulation of contaminants near the first side end S-2 d of thefunctional module. The foldable display device may comprise a bendingprotection layer disposed on the outer surface of the bent region. Thebending protection layer may a first portion included in the at leastthe portion of the height-compensating layer structure. The firstportion of the bending protection layer may contact the first side endS-2 d of the functional module.

Example embodiments are directed to a mobile terminal with a foldabledisplay device. The foldable display device may provide an imagedisplayed from the mobile terminal. The mobile terminal is for a finalhuman consumer. The final human consumer may communicate, access data,download data, or handle information by using the mobile terminal. Thefoldable display device may a lower module, a double-sided adhesivelayer, a display module, a functional module, and a window module. Thelower module may have a first side end S-4 d disposed in a first sidearea of the foldable display device. The double-sided adhesive layer maybe on the lower module. The display module may be on the double-sidedadhesive layer. The display module may include, as one body, a mainregion, a sub region, and a bent region. The main region may include adisplay area disposed over the lower module. The main region may have afirst side end S-MR disposed in the first side area. The display areamay include an emissive unit having a first electrode, a secondelectrode, and an emission layer between the first and secondelectrodes. The display area may have a first side end S-DPA disposed inthe first side area. The sub region may be disposed under the lowermodule. The sub region may overlap the main region. The sub region mayhave a first side end S-SR disposed in the first side area. The bentregion may be disposed in the first side area. The bent region may belocated between the first side end S-MR of the main region and the firstside end S-SR of the sub region such that the bent region is bentbetween the first side end S-MR of the main region and the first sideend S-SR of the sub region. The bent region may have an outer surfacebetween an upper surface of the main region and a lower surface of thesub region. The bent region may have an inner surface between a lowersurface of the main region and an upper surface of the sub region. Thefunctional module may be disposed on the main region. The functionalmodule may have a first side end S-2 d disposed in the first side area.The window module may be disposed on the functional module. The windowmodule may have a first side end S-3 d disposed in the first side area.The display module may include a lower inorganic encapsulation structureand an upper encapsulation structure. The emissive unit may be locatedbetween the lower inorganic encapsulation structure and the upperencapsulation structure. Both of the upper encapsulation structure andthe window module may be flexible. The first side end S-MR of the mainregion may be disposed outwardly away from the first side end S-DPA ofthe display area in plan view. The first side end S-MR of the mainregion may be not disposed inwardly away from the first side end S-4 dof the lower module in plan view. The upper encapsulation structure mayhave a lower surface comprising only at least one inorganic material.The lower inorganic encapsulation structure and the upper encapsulationstructure may directly contact each other to encapsulate the emissiveunit. The foldable display device may comprise a height-compensatinglayer structure having at least a portion disposed on the main region,disposed outwardly away from the first side end S-2 d of the functionalmodule in plan view, and disposed inwardly away from the first side endS-MR of the main region in plan view. The height-compensating layerstructure may have, between the main region and the window module, aheight substantially the same as a distance between the main region andthe window module. The height-compensating layer structure may supportthe window module, which is flexible, to prevent the window module frombending. The height-compensating layer structure may prevent anaccumulation of contaminants near the first side end S-2 d of thefunctional module. The foldable display device may comprise a bendingprotection layer disposed on the outer surface of the bent region. Thebending protection layer may a first portion included in the at leastthe portion of the height-compensating layer structure. The firstportion of the bending protection layer may contact the first side endS-2 d of the functional module.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention, and together with the description serve to explain theinventive concepts.

FIG. 1 is a plan view of a display device according to an exemplaryembodiment.

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1.

FIG. 3 is a cross-sectional view taken along line II-II′ of a flexibledisplay module included in a display device of FIG. 1 according to anexemplary embodiment.

FIG. 4 is a cross-sectional view taken along line III-III′ of FIG. 1.

FIGS. 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 are cross-sectionalviews of display devices according to exemplary embodiments.

FIGS. 16, 17, 18, 19, and 20 are cross-sectional views of displaydevices according to exemplary embodiments.

FIG. 21 is a cross-sectional view of a display device according toanother exemplary embodiment.

FIG. 22 is a plan view of a color filter included in a display deviceaccording to another exemplary embodiment.

FIG. 23 is a cross-sectional view taken along line IV-IV′ of FIG. 22.

FIGS. 24 and 25 are cross-sectional views of display devices accordingto exemplary embodiments.

FIG. 26 is a cross-sectional view of a display device according to yetanother exemplary embodiment.

FIG. 27 is a cross-sectional view of a display module included in thedisplay device according to an exemplary embodiment.

FIG. 28 is a cross-sectional view of a display device according toanother exemplary embodiment.

FIGS. 29 and 30 are views for illustrating a process of fabricating adisplay device according to another exemplary embodiment.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various exemplary embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form in order to avoid unnecessarilyobscuring various exemplary embodiments. Further, various exemplaryembodiments may be different, but do not have to be exclusive. Forexample, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the D1-axis, the D2-axis,and the D3-axis are not limited to three axes of a rectangularcoordinate system, such as the x, y, and z-axes, and may be interpretedin a broader sense. For example, the D1-axis, the D2-axis, and theD3-axis may be perpendicular to one another, or may represent differentdirections that are not perpendicular to one another. For the purposesof this disclosure, “at least one of X, Y, and Z” and “at least oneselected from the group of X, Y, and Z” may be construed as X only, Yonly, Z only, or any combination of two or more of X, Y, and Z, such as,for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should notnecessarily be construed as limited to the particular illustrated shapesof regions, but are to include deviations in shapes that result from,for instance, manufacturing. In this manner, regions illustrated in thedrawings may be schematic in nature and the shapes of these regions maynot reflect actual shapes of regions of a device and, as such, are notnecessarily intended to be limiting.

As is customary in the field, some exemplary embodiments are describedand illustrated in the accompanying drawings in terms of functionalblocks, units, and/or modules. Those skilled in the art will appreciatethat these blocks, units, and/or modules are physically implemented byelectronic (or optical) circuits, such as logic circuits, discretecomponents, microprocessors, hard-wired circuits, memory elements,wiring connections, and the like, which may be formed usingsemiconductor-based fabrication techniques or other manufacturingtechnologies. In the case of the blocks, units, and/or modules beingimplemented by microprocessors or other similar hardware, they may beprogrammed and controlled using software (e.g., microcode) to performvarious functions discussed herein and may optionally be driven byfirmware and/or software. It is also contemplated that each block, unit,and/or module may be implemented by dedicated hardware, or as acombination of dedicated hardware to perform some functions and aprocessor (e.g., one or more programmed microprocessors and associatedcircuitry) to perform other functions. Also, each block, unit, and/ormodule of some exemplary embodiments may be physically separated intotwo or more interacting and discrete blocks, units, and/or moduleswithout departing from the scope of the inventive concepts. Further, theblocks, units, and/or modules of some exemplary embodiments may bephysically combined into more complex blocks, units, and/or moduleswithout departing from the scope of the inventive concepts.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

FIG. 1 is a plan view of a display device according to an exemplaryembodiment. FIG. 2 is a cross-sectional view taken along line I-I′ ofFIG. 1.

Referring to FIGS. 1 and 2, a display device 100 may have asubstantially rectangular shape when viewed from the top. Moreparticular, the display device 100 may have a rectangular shape havingrounded corners when viewed from the top, but the inventive concepts arenot limited thereto. For example, the display device 100 may have arectangular shape having corners at the right angle.

As used herein, “top” and “upper surface” in the thickness directionrefer to the side of the display panel in which images are displayed inthe unfolded state, whereas “bottom” and “lower surface” refer to theopposite side of the display panel in the unfolded state, unless statedotherwise. In addition, “upper side,” “lower side,” “left side,” and“right side” in the plane are defined when the display surface is viewedfrom the top.

The display device 100 may be bent with respect to a folding axis AXIS_Fextended in the vertical direction. More particularly, the displaydevice 100 may be switchable between the folded state (e.g., folded withrespect to the folding axis AXIS_F) and the unfolded state. Theswitching between the folded state and the unfolded state of the displaydevice 100 will be described in more detail below.

As used herein, the term “foldable” may refer to partial folding, entirefolding, rollable, in-folding, out-folding, and flexible. In addition,the term “display device” is a display part in an information device,such as a television and a mobile terminal for a final human consumer,as well as an optical device such as a luminaire.

The display device 100 may include a display module 210 (or a flexibledisplay module, a display panel, a flexible display panel), an upperflexible module 220 (or a flexible upper module), a lower flexiblemodule 230 (or a flexible lower module), and a rigid layer 240. Thedisplay device 100 may further include double-sided adhesive layersNAD1, NAD2, NAD3, and 250 each disposed (or interposed) between two ofthe display module 210, the upper flexible module 220, the lowerflexible module 230, and the rigid layer 240.

The display module 210 may display an image by receiving data signals.As the display module 210, one of an organic light-emitting displaymodule, a liquid-crystal display module, a plasma display module, anelectrophoretic display module, an electro-wetting display module, aquantum-dot emission display module, a micro LED display module, etc.may be employed. FIG. 2 shows an organic light-emitting display moduleas the display module 210.

The display module 210 may include a flexible substrate including aflexible polymer material, such as polyimide. Accordingly, the displaymodule 210 may be curved, bent, folded, or rolled.

The display module 210 may have a shape substantially similar to that ofthe display device 100 when viewed from the top. However, the inventiveconcepts are not limited to the particular shape of the display module210. For example, at least one side (e.g., the left side) of the displaymodule 210 may be curved or bent at the right angle. A circuit board 422(see FIG. 4) including wires for transmitting signals to drive thedisplay module 210 may be connected through at least one side of thedisplay module 210. The circuit board 422 may be disposed to overlap thedisplay module 210 in the thickness direction thereof. The circuit board422 will be described in more detail below with reference to FIG. 4.

The display module 210 may include a display area DPA (or an emissionarea) where images are displayed, and a non-display area NDA (or anon-emission area) where no image is displayed.

The display area DPA may be disposed at the center of the display module210. The display area DPA may include pixels (or electroluminescentunits). The pixels will be described later in more detail with referenceto FIG. 3.

The display area DPA may have a rectangular shape with rounded corners.However, the inventive concepts are not limited to the shapes of thedisplay area DPA. For example, the display area DPA may have variousshapes, such as a square, a rectangle, or other polygonal or circularshape, elliptical shape, etc.

The non-display area NDA may be located around the display area DPA. Aportion of the display module 210 other than the display area DPA may bethe non-display area NDA. The non-display area NDA may refer to the areafrom the outer boundary of the display area DPA to the edge of thedisplay module 210. In the non-display area NDA, signal wiring forapplying a signal to the display area DPA or drive circuits may bedisposed. In addition, the outermost part of a black matrix may bedisposed in the non-display area NDA.

In addition, the display module 210 may include a foldable region FR (ora bendable region). The foldable region FR will be described in detaillater together with the rigid layer 240.

The upper flexible module 220 may overlap with the display module 210 inthe thickness direction and may be disposed on the display module 210.The upper flexible module 220 may be used to adjust the location of aneutral plane NP of the display device 100 together with the lowerflexible module 230. When the display device 100 is bent or folded, atensile stress occurs on one side of the display device 100 with respectto the neutral plane NP, while a compressive stress occurs on the otherside of the display device 100 with respect to the neutral plane NP.Between the opposing sides, there is a plane that is neither expandednor contracted, which is defined as the neutral plane NP. There issubstantially no bending stress on the neutral plane NP. For example,the upper flexible module 220 (or a high neutral plane control portion(HNPC) including the upper flexible module 220) and the lower flexiblemodule 230 (or a low neutral plane control portion (LNPC) including thelower flexible module 230) may be used to place the neutral plane NP ofthe display device 100 in the display module 210 (e.g., in the layer onwhich the driving transistors of the display module 210 are formed).

The upper flexible module 220 may include a flexible function module 221and a flexible window module 222.

The flexible function module 221 may include at least one functionallayer. The functional layer may perform a touch sensing feature, a colorfiltering feature, a color conversion feature, a polarization feature, abiometric information recognition feature (for example, a fingerprintrecognition feature), etc. The functional layer may be a sheet layermade of a sheet, a film layer made of a film, a thin film layer, acoating layer, a panel, a plate or the like. A single functional layermay be made up of a single layer or a plurality of thin films or coatinglayers stacked on one another. For example, the functional layer may bea touch sensing panel, a color filter, an optical film, a fingerprintsensing panel, or the like.

The flexible function module 221 may include an optical film, such as amicro-lens and a prism film. The optical film may be omitted.

The flexible window module 222 (or window) may be disposed on theflexible function module 221. The first upper double-sided adhesivelayer NAD1 may be disposed (or interposed) between the flexible windowmodule 222 and the flexible function module 221. As used herein, thefirst upper double-sided adhesive layer NAD1 has upper and lowersurfaces that are adhesive. For example, the first upper double-sidedadhesive layer NAD1 may be an optical clear adhesive (OCA).

The flexible window module 222 covers and protects the display module210. The flexible window module 222 may be made of a transparentmaterial. The flexible window module 222 may include plastic. Theflexible window module 222 may have flexibility.

Examples of plastics applicable to the flexible window module 222 mayinclude, but are not limited to, polyimide, polyacrylate,polymethylmethacrylate (PMMA), polycarbonate (PC),polyethylenenaphthalate (PEN), polyvinylidene chloride, polyvinylidenedifluoride (PVDF), polystyrene, ethylene vinylalcohol copolymer,polyethersulphone (PES), polyetherimide (PEI), polyphenylene sulfide(PPS), polyallylate, tri-acetyl cellulose (TAC), cellulose acetatepropionate (CAP), and the like. The flexible window module 222 mayinclude one or more of the plastic materials listed above.

The second upper double-sided adhesive layer NAD2 may be disposedbetween the upper flexible module 220 (or the flexible function module221) and the display module 210, and the upper flexible module 220 maybe attached on (or coupled with) the display module 210 by the secondupper double-sided adhesive layer NAD2. The second upper double-sidedadhesive layer NAD2 may have substantially the same thickness as thefirst upper double-sided adhesive layer NAD1. However, the inventiveconcepts are not limited to a particular thickness of the adhesivelayers, and, for example, the second upper double-sided adhesive layerNAD2 may have a thickness substantially different from that of the firstupper double-sided adhesive layer NAD1.

The lower flexible module 230 may overlap with the display module 210 inthe thickness direction and may be disposed below the display module210.

The lower flexible module 230 may include at least one functional layer.The functional layer may perform a heat dissipation function, anelectromagnetic wave shielding function, a grounding function, abuffering function, a strength enhancing function, a supportingfunction, a bonding function, a pressure sensing function, and adigitizing function. The functional layer may be, for example, asupporting substrate, a heat-radiating layer, an electromagnetic waveshielding layer, an impact absorbing layer, a bonding layer, a pressuresensor, a digitizer, etc.

The lower flexible module 230 may have a light transmittance relativelyless than that of the upper flexible module 220. More particularly, theupper flexible module 220 may have a relatively high light transmittanceand may transmit light (or an image) emitted from the display area DPAof the display module 210 toward the top. The lower flexible module 230may have a relatively low light transmittance and may block light thatis downwardly emitted from the display area DPA of the display module210 and reflected.

The lower double-sided adhesive layer NAD3 may be disposed between thelower flexible module 230 and the display module 210. The lower flexiblemodule 230 may be attached to the lower surface of the display module210 by the lower double-sided adhesive layer NAD3. Similarly to thefirst and second upper double-sided adhesive layers NAD1 and NAD2, thelower double-sided adhesive layer NAD3 has upper and lower surfaces thatare adhesive. For example, the lower double-sided adhesive layer NAD3may be a press sensitive adhesive (PSA).

The lower flexible module 230 may include an impact absorbing layer. Theimpact absorbing layer may be used to block the impact applied from theoutside (for example, from the bottom) from being transmitted to thedisplay module 210. For example, the impact absorbing layer may be madeof a material including polyurethane (PU), thermoplastic polyurethane(TPU), silicone, polydimethylacrylamide (PDMA), etc.

The rigid layer 240 may overlap with the lower flexible module 230 inthe thickness direction and may be disposed below the lower flexiblemodule 230.

The rigid layer 240 may be made of a material including metal, such asstainless steel (SUS) and aluminum, or a polymer material, such aspolymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol(PVA), acrylonitrile-butadiene-styrene (ABS) and polyethyleneterephthalate (PET). The rigid layer 240 may prevent the display module210 from being bent by an external force or may mitigate (or reduce) thedegree of bending (e.g., bending angle, bending radius of curvature) ofthe display module 210. More particularly, the rigid layer 240 canmaintain the display module 210 in a relatively flat state even if anexternal force is applied. The rigid layer 240 may be rigid orsemi-rigid. For example, the rigid layer 240 may be a stainless steelfilm having a thickness of 150 μm to 200 μm. As another example, therigid layer 240 may be an aluminum film having a thickness of 150 μm to200 μm.

The double-sided adhesive layer 250 may be disposed between the rigidlayer 240 and the lower flexible module 230, and the rigid layer 240 maybe attached to the lower flexible module 230 by the double-sidedadhesive layer 250.

A protrusion or a groove (or hole) may be formed in the lower surface ofthe rigid layer 240 so that a housing may be coupled with the rigidlayer 240 (or the display device 100) by the protrusion or groove.

The rigid layer 240 may include a first plate 241 (or a first part) anda second plate 242 (or a second part) that are separated from each otherin the left-and-right direction (or in the horizontal direction). Thefirst plate 241 and the second plate 242 may be disposed on the sameplane and spaced apart from each other by a reference distance D0 in thehorizontal direction. For example, the reference distance D0 may be 0.1mm or less. The first and second plates 241 and 242 are, but not limitedto, mutually symmetric with respect to a folding line FL (e.g., the linemeeting the folding axis AXIS_F in the thickness direction). Forexample, the first and second plates 241 and 242 may be mutuallyasymmetric with respect to the folding line FL.

Although the first plate 241 and the second plate 242 are depicted asbeing spaced apart from each other in FIG. 2, this is merelyillustrative to emphasize that the first plate 241 and the second plate242 are separated from each other (or mutually non-contiguous). Forexample, the inner side surface of the first plate 241 may come incontact with at least a portion of the inner side surface of the secondplate 242.

According to an exemplary embodiment, the first plate 241 and the secondplate 242 may have a shape whose thickness decreases toward the foldingline FL. For example, the thickness of the first plate 241 and thesecond plate 242 may be reduced stepwise. As another example, thethickness of the first plate 241 and the second plate 242 may becontinuously reduced. When the thickness of the first plate 241 and thesecond plate 242 decreases toward the folding line FL, the flexibilityof the first plate 241 and the second plate 242 may be greater near thefolding line FL than at the other portions.

The double-sided adhesive layer 250 may be disposed between the firstand second plates 241 and 242 (or the rigid layer 240) and the lowerflexible module 230, so that the first and second plates 241 and 242 maybe coupled to the lower portion of the lower flexible module 230 by thedouble-sided adhesive layer 250.

The double-sided adhesive layer 250 may include a first double-sidedadhesive layer 251 (or a third part) and a second double-sided adhesivelayer 252 (or a fourth part) that are separated from each other.

The first double-sided adhesive layer 251 overlaps with the displaymodule 210 (or the lower flexible module 230) in the thickness directionin a first non-foldable region NFR1, and may be disposed between thelower flexible module 230 and the first plate 241. Then, the first plate241 may be coupled to the lower flexible module 230 by the firstdouble-sided adhesive layer 251. Similarly, the second double-sidedadhesive layer 252 overlaps with the display module 210 (or the lowerflexible module 230) in the thickness direction in a second non-foldableregion NFR2, and may be disposed between the lower flexible module 230and the second plate 242. Then, the second plate 242 may be coupled tothe lower flexible module 230 by the second double-sided adhesive layer252.

The first double-sided adhesive layer 251 and the second double-sidedadhesive layer 252 may be located on the same plane and may be spacedapart from each other by a first distance D1 in the horizontaldirection. The first distance D1 may be relatively greater than thereference distance D0. For example, the first distance D1 may be 10 mmor less. The first double-sided adhesive layer 251 and the seconddouble-sided adhesive layer 252 may be symmetrical with respect to thefolding axis AXIS_F (or the folding plane in which the folding axis isextended in the thickness direction or the folding line).

The inner side surface of the first plate 241 may be relatively closerto the folding axis AXIS_F than the inner side surface of the firstdouble-sided adhesive layer 251, and the inner side surface of thesecond plate 242 may be relatively closer to the folding line FL thanthe inner side surface of the second double-sided adhesive layer 252.

The foldable region FR and the first and second non-foldable regionsNFR1 and NFR2 of the display module 210 (or the display device 100) maybe set or defined by the first double-sided adhesive layer 251 and thesecond double-sided adhesive layer 252. The first and secondnon-foldable regions NFR1 and NFR2 refer to the areas where the firstand second plates 241 and 242 are coupled with the lower flexible module230 by the first and second double-sided adhesive layers 251 and 252,respectively. The first and second non-foldable regions NFR1 and NFR2may have a small degree of bending by an external force, and may have agenerally flat state. More particularly, the first and secondnon-foldable regions NFR1 and NFR2 may be defined as areas where therigid layer 240 (or the first and second plates 241 and 242), thedouble-sided adhesive layer 250 (or the first and second double-sidedadhesive layers 251 and 252), and the display module 210 are alloverlapped with one another in the thickness direction and coupled (orattached) with one another. The foldable region FR refers to an areawhich is not directly coupled with (or supported by) the first plate 241and the second plate 242, and may have a large degree of bending from anexternal force. For example, given the same external force, the degreeof deformation (for example, the degree of bending) of the foldableregion FR may be about three times or more than the degree ofdeformation of the first and second non-foldable regions NFR1 and NFR2.The foldable region FR may be switched from the folded state to theexpanded state by an external force, or vice versa.

As shown in FIG. 1, the foldable region FR has a rectangular shape andhas a predetermined width in the horizontal direction with respect tothe folding axis AXIS_F extending in the up-and-down direction (orvertical direction), and may extend in the vertical direction from theupper side surface to the lower side surface. The width of the foldableregion FR may be substantially equal to or substantially similar to thefirst distance D1 between the first and second double-sided adhesivelayers 251 and 252.

The first non-foldable region NFR1 may be connected to one side of thefoldable region FR (e.g., the left side of the folding axis AXIS_F). Thesecond non-foldable region NFR2 may be connected to the other side ofthe foldable region FR (e.g., the right side of the folding axisAXIS_F). The width of the first non-foldable region NFR1 may besubstantially equal to or substantially different from the width of thesecond non-foldable region NFR2.

As described above, the foldable region FR of the display device 100 maybe defined by the first and second double-sided adhesive layers 251 and252, and the neutral plane NP may be aligned with the display module 210by the high neutral plane control portion HNPC and the low neutral planecontrol portion LNPC.

FIG. 3 is a cross-sectional view taken along line II-II′ of a flexibledisplay module included in a display device of FIG. 1 according to anexemplary embodiment.

A first organic flexible layer 311 (or a first substrate) may be aninsulating substrate. In an exemplary embodiment, the first organicflexible layer 311 may include a material such as a polymer resin. Thepolymer material may be polyethersulphone (PES), polyamide (PA),polyacrylate (PAR), polyetherimide (PEI), polyethylenenapthalate (PEN),polyethyleneterepthalate (PET), polyphenylenesulfide (PPS),polyallylate, polyimide (PI), polycarbonate (PC), cellulosetriacetate(CAT), cellulose acetate propionate (CAP), or combinations thereof.

A first inorganic layer 321 (or a buffer layer) may be disposed on thefirst organic flexible layer 311. In an exemplary embodiment, the firstinorganic layer 321 may include one of a silicon nitride (SiN_(x))layer, a silicon oxide (SiO₂) layer, and a silicon oxynitride(SiO_(x)N_(y)) layer.

A semiconductor layer including a semiconductor pattern ACT may bedisposed on the first inorganic layer 321. The first inorganic layer 321is disposed between the semiconductor pattern ACT and the first organicflexible layer 311 to increase the adhesion and also blocks moisture andoxygen which may be transferred from the first organic flexible layer311 to the semiconductor pattern ACT, and so on. It is to be noted thatthe first inorganic layer 321 may be eliminated depending on the kind ofthe first organic flexible layer 311, process conditions, etc. Thesemiconductor pattern ACT will be described as an example of thesemiconductor layer. In an exemplary embodiment, the semiconductorpattern ACT may be made of one selected from polycrystalline silicon,single crystal silicon, low-temperature polycrystalline silicon,amorphous silicon and oxide semiconductor or a mixture thereof. In anexemplary embodiment, the semiconductor pattern ACT may include achannel region ACTa doped with no impurity, and a source region ACTb anda drain region ACTc doped with impurities. The source region ACTb islocated on one side of the channel region ACTa and is electricallyconnected to a source electrode SE described later. The drain regionACTc is located on the other side of the channel region ACTa and iselectrically connected to a drain electrode DE described later.

A second inorganic layer 322 (or a first insulating layer) may bedisposed on the semiconductor layer including the semiconductor patternACT. In an exemplary embodiment, the second inorganic layer 322 may be agate insulating layer. In an exemplary embodiment, the second inorganiclayer 322 may be made of an inorganic insulating material such assilicon oxide (SiO_(x)) and silicon nitride (SiN_(x)).

A gate conductor including the gate electrode GE may be disposed on thesecond inorganic layer 322. The gate electrode GE may overlap with thesemiconductor pattern ACT. For example, the gate conductor may includeat least one of an aluminum (Al)-based metal including an aluminumalloy, a silver (Ag)-based metal including a silver alloy, a copper(Cu)-based metal including a copper alloy, a molybdenum (Mo)-based metalincluding molybdenum alloy, chromium (Cr), titanium (Ti), and tantalum(Ta).

A third inorganic layer 323 (or a second insulating layer) may bedisposed on the gate conductor including the gate electrode GE. Thethird inorganic layer 323 may be made of an inorganic insulatingmaterial, such as silicon oxide (SiO_(x)) and silicon nitride (SiN_(x)).

A data conductor including the source electrode SE and the drainelectrode DE may be disposed on the third inorganic layer 323. Thesource electrode SE and the drain electrode DE are disposed on the thirdinorganic layer 323 such that they are spaced apart from each other. Thedata conductor may include at least one of metal, an alloy thereof, ametal nitride, a conductive metal oxide, and a transparent conductivematerial. In an exemplary embodiment, the data conductor may have asingle-layer structure or a multi-layers structure including nickel(Ni), cobalt (Co), titanium (Ti), silver (Ag), copper (Cu), molybdenum(Mo), aluminum (Al), beryllium (Be), niobium (Nb), gold (Au), iron (Fe),selenium (Se), tantalum (Ta), etc. In addition, an alloy formed byadding at least one of titanium (Ti), zirconium (Zr), tungsten (W),tantalum (Ta), niobium (Nb), platinum (Pt), hafnium (Hf), oxygen (O),and nitrogen (N) to the above-listed metal may be used as the materialsof the source electrode SE and the drain electrode DE.

The semiconductor pattern ACT, the gate electrode GE, the sourceelectrode SE, and the drain electrode DE described above form aswitching element. Although the switching element is depicted as atop-gate transistor in FIG. 3, the type of the switching element is notlimited thereto. For example, the switching element may be a bottom-gatetransistor.

A fourth inorganic layer 324 is disposed on the third inorganic layer323. The fourth inorganic layer 324 may include an inorganic material,such as silicon oxide, silicon nitride and silicon oxynitride.

A fifth inorganic layer 325 may be disposed on the fourth inorganiclayer 324 so as to cover the data conductor. A first contact hole CNT1may be formed in the second inorganic layer 322, the third inorganiclayer 323, and the fourth inorganic layer 324 by which at least a partof the drain electrode DE is exposed.

The first to fifth inorganic layers 321 to 325 may form a lowerencapsulation structure 320.

A lower electrode LE (or a pixel electrode) may be disposed on the fifthinorganic layer 325. The lower electrode LE may be electricallyconnected to the drain electrode DE exposed via the first contact holeCNT1. More particularly, the lower electrode LE may be an anode, whichmay be a hole injection electrode. When the lower electrode LE is ananode electrode, the lower electrode LE may include a material having ahigh work function to facilitate hole injection. In addition, the lowerelectrode LE may be a reflective electrode, a semi-transparentelectrode, or a transparent electrode. In an exemplary embodiment, thelower electrode LE may include a reflective material. The reflectivematerial may include, for example, at least one of silver (Ag),magnesium (Mg), chromium (Cr), gold (Au), platinum (Pt), nickel (Ni),copper (Cu), tungsten (W), aluminum (Al), aluminum-lithium (Al—Li),magnesium-indium (Mg—In), and magnesium-silver (Mg—Ag).

In an exemplary embodiment, the lower electrode LE may have a singlelayer structure or a multiple layers structure in which two or morematerials are stacked on one another.

When the lower electrode LE is made up of multiple layers, the lowerelectrode LE may include, for example, a reflective layer and atransparent or translucent electrode disposed on the reflective layer.As another example, the lower electrode LE may include a reflectivelayer and a transparent or translucent electrode disposed under thereflective layer. For example, the lower electrode LE may have, but isnot limited to, a three-layer structure of ITO/Ag/ITO.

The transparent or semi-transparent electrode may be made of at leastone of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide(ZnO), Indium Oxide (In₂O₃), indium gallium oxide (IGO), and aluminumzinc oxide (AZO).

A pixel defining layer PDL may be disposed over the lower electrode LE.The pixel defining layer PDL includes an opening exposing at least apart of the lower electrode LE. The pixel defining layer PDL may includean organic material or an inorganic material. In an exemplaryembodiment, the pixel defining layer PDL may include a material such asa photoresist, a polyimide resin, an acrylic resin, a silicon compound,and a polyacrylic resin.

An intermediate layer IL (or an organic emissive layer) may be disposedover the lower electrode LE and the pixel defining layer PDL. Morespecifically, the intermediate layer IL may be disposed on the portionof the lower electrode LE that is exposed via the opening of the pixeldefining layer PDL. In an exemplary embodiment, the intermediate layerIL may cover at least a part of the sidewall of the pixel defining layerPDL.

In an exemplary embodiment, the intermediate layer IL may emit light ofone of red, blue, and green colors. In another exemplary embodiment, theintermediate layer IL may emit white light or emit light of one of cyan,magenta and yellow. When the intermediate layer IL emits white light, itmay include a white light-emitting material or may have a stackstructure of a red light-emitting layer, a green light-emitting layer,and a blue light-emitting layer to emit white light.

An upper electrode UE (or a common electrode) may be disposed over theintermediate layer IL and the pixel defining layer PDL. The upperelectrode UE may be formed throughout the entire surface of theintermediate layer IL and the pixel defining layer PDL, for example. Inan exemplary embodiment, the upper electrode UE may be a cathodeelectrode. In an exemplary embodiment, the upper electrode UE mayinclude at least one of Al, Ag, and Mg. In addition, the upper electrodeUE may be made of a material having a low work function. In an exemplaryembodiment, the upper electrode UE may be made of at least one of indiumtin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide(In₂O₃), indium gallium oxide (IGO), and aluminum zinc oxide (AZO).

The above-described lower electrode LE, the intermediate layer IL, andthe upper electrode UE may form an organic light-emitting diode OLED.However, the inventive concepts are not limited thereto, and the organiclight-emitting diode OLED may be a multiple layer structure furtherincluding a hole injection layer (HIL), a hole transport layer (HTL), anelectron transport layer (ETL), and an electron injection layer (EIL).

An encapsulation layer 330 (or an upper encapsulation multilayer) may bedisposed over the upper electrode UE. The encapsulation layer 330 may beused to prevent moisture, air, etc., which may be introduced from theoutside, from permeating into the organic light-emitting diode OLED. Inan exemplary embodiment, the encapsulation layer 330 may include a sixthinorganic layer 331, an organic layer 332, and a seventh inorganic layer333.

The sixth inorganic layer 331 may be disposed on the upper electrode UE.The sixth inorganic layer 331 may include at least one selected from thegroup consisting of silicon oxide (SiO_(x)), silicon nitride (SiN_(x))and silicon oxynitride (SiON_(x)).

The organic layer 332 may be disposed on the sixth inorganic layer 331.The organic layer 332 may include one of epoxy, acrylate, and urethaneacrylate. The organic layer 332 may be used to provide a flat surfaceover the level difference created by the pixel defining layer PDL.

The seventh inorganic layer 333 may be disposed on the organic layer332. The seventh inorganic layer 333 may include at least one of siliconoxide (SiO_(x)), silicon nitride (SiN_(x)), and silicon oxynitride(SiON_(x)).

Although each of the sixth inorganic layer 331, the organic layer 332,and the seventh inorganic layer 333 shown in FIG. 3 is made up of asingle layer, the inventive concepts are not limited thereto, and atleast one of the sixth inorganic layer 331, the organic layer 332 andthe seventh inorganic layer 333 may be made up of multiple layers.

In another exemplary embodiment, the encapsulation layer 330 may includea hexamethyldisiloxane (HMDSO) layer. More specifically, theencapsulation layer 330 may include the sixth inorganic layer 331, theseventh inorganic layer 333 and a HMDSO layer disposed between the sixthinorganic layer 331 and the seventh inorganic layer 333. In particular,the above-described organic layer 332 may be replaced with the HMDSOlayer.

In an exemplary embodiment, the HMDSO layer may be formed in the samechamber as the sixth inorganic layer 331 after it is formed, which maysimplify the process of forming the encapsulation layer 330. Inaddition, as the encapsulation layer 330 includes the HMDSO layer thatis capable of absorbing stress, the encapsulation layer 330 can havesufficient flexibility.

An inorganic-inorganic closed loop CL may be formed along the outerperiphery of the display module 210 on the upper surface of the fifthinorganic layer 325. In an exemplary embodiment, the inorganic-inorganiccontact closed loop CL may be formed to substantially surround thedisplay area in a plan view. The inorganic-inorganic closed loop CL mayrefer to a portion in which an inorganic upper surface PLANE1 of thelower encapsulation structure 320 and an inorganic lower surface PLANE2of the upper encapsulation multilayer 330 are in direct contact witheach other. In this manner, moisture or the like permeating into thespace between the fifth inorganic layer 325 and the sixth inorganiclayer 331 may be prevented by the inorganic-inorganic closed loop CL.

FIG. 4 is a cross-sectional view taken along line III-III′ located inone side area of the display device 100 shown in FIG. 1.

Referring to FIG. 4, the display module 210 may include a main region MRand a bent region BR (or a bending region) connected to one side (i.e.,a side end) S-MR of the main region MR. The display module 210 mayfurther include a sub region SR having one side (i.e., a side end) S-SRconnected to the bent region BR. The sub region SR may be overlappedwith the main region MR in the thickness direction.

The main region MR is a planar area located in one plane, and mayinclude the display area DPA having one side (i.e., a side end) S-DPA.

The bent region BR is connected to one side S-MR of the main region MR.For example, the bent region BR may be connected to the right side S-MRof the main region MR. The width of the bent region BR may be, but isnot limited to, relatively smaller than the width (e.g., the width ofthe right side) of the main region MR.

In the bent region BR, the display module 210 may be bent downward(i.e., in the direction away from the display surface) with a curvatureR. Although the bent region BR may have a constant radius of curvature,the inventive concepts are not limited thereto. For example, the bentregion BR may have a substantially different radius of curvature foreach section. As the display module 210 is bent in the bent region BR,the surface of the display module 210 is reversed. More specifically,the surface of the display module 210 facing upward may be changed toface outward in the bent region BR, and then may be changed to facedownward.

The sub region SR is extended from the bent region BR. The sub region SRmay be extended in a direction parallel to the main region MR after thedisplay device 100 has been bent. The sub region SR may overlap with themain region MR in the thickness direction of the display module 210. Thesub region SR may overlap with the non-display area NDA at the edge ofthe main region MR and may also overlap with the display area DPA of themain region MR.

A fourth double-sided adhesive layer NAD4 may be disposed between thesub region SR of the display module 210 and the rigid layer 240 (or thesecond plate 242), and the sub region SR of the display module 210 maybe attached to the rigid layer 240.

A plurality of wirings may be disposed in the bent region BR and the subregion SR. The wiring in the bent region BR may be connected to acircuit layer of the main region MR and may be extended to thesub-region SR. The wiring extended to the sub region SR may be connectedto the circuit board 422.

The circuit board 422 may be a flexible printed circuit board. Thecircuit board 422 may be provided, but is not limited to, in the form offilm-on-plastic. For example, the upper surface of an end of the circuitboard 422 may be attached on the wire on the lower surface of thedisplay module 210 in the sub region SR. The circuit board 422 may beattached via an anisotropic conductive film.

A protective layer 411 (or a bent region protective layer) may bedisposed on the display module 210 in the bent region BR and the subregion SR. The protective layer 411 covers and protects driving wiring.In addition, the protective layer 411 may reinforce the strength of aflexible substrate or to mitigate stress in the bent region BR. Theprotective layer 411 exposes a part of the wiring (e.g., wiring pad PAD)located in the sub region SR.

A part of the protective layer 411 may be extended to the main region MRof the display module 210. Even if the protective layer 411 is disposedon the main region MR, the protective layer 411 may be located in thenon-display area NDA of the main region MR, and may not be extended tothe display area DPA. The protective layer 411 may not overlap theflexible function module 221 (for example, a polarizing film).

In an exemplary embodiment, the protective layer 411 may include anorganic coating layer, such as polyimide, acrylate, and epoxy. Inanother exemplary embodiment, the protective layer 411 may be attachedin the form of a protective layer.

The protective layer 411 may have a thickness relatively less than thethickness of the flexible function module 221. In this case, contaminantDUST may be introduced between the flexible window module 222 and theprotective layer 411 in a direction D F toward the side surface (orsidewall) of the flexible functional module 221 and accumulated on theside surface (or sidewall) of the flexible functional module 221. Thecontaminant DUST may be introduced when the outer periphery of thewindow module 222 or the display module 210 is processed with a laser.The contaminant DUST may be carbide. In addition, the window module 222may be spaced apart from the protective layer 411 due to the thicknessof the protective layer 411, such that the window module 222 may be bentwithout being supported thereby. Such problems rarely occur when therigid glass is employed in existing devices. However, when the windowmodule 222 having flexibility is employed, such a phenomenon may occuron the window module 222 during a laser process (such as a laserablation process), which may generate contaminants DUST, such ascarbide.

The outer side surface of the protective layer 411 at a center point B1of the bent region BR may be on the same plane with an outer sidesurface (i.e., a side end) S-3 d of the flexible window module 222. Inan exemplary embodiment, an outermost portion of the outer surface ofthe protection layer 411 is formed on the same plane as the outer sidesurface S-3 d of the flexible window module 222, such that the outermostportion of the protection layer 411 is located just under the outer sidesurface S-3 d of the flexible window module 222.

Referring to FIG. 5, a display device 100_1 is substantially differentfrom the display device 100 of FIG. 4 in that the display device 100_1includes a protective layer 511 and an upper flexible module 520.

The protective layer 511 may be interposed between a flexible windowmodule 522 and the display module 210. The protective layer 511 may bespaced apart from the flexible function module 221 by a predeterminedgap GAP in the left-and-right direction. The predetermined gap GAP maybe substantially zero. Then, one side surface of the protective layer511 may be in contact with one side surface of the flexible functionmodule 221.

The thickness of the protective layer 511 may be substantially equal tothe total thickness of the flexible function module 221 and the firstand second upper double-sided adhesive layers NAD1 and NAD2. Forexample, the thickness of the protective layer 511 may be substantiallyequal to the sum of the thickness of the flexible function module 221,the thickness of the first upper double-sided adhesive layer NAD1, andthe thickness of the second upper double-sided adhesive layer NAD2.

In this case, the protective layer 511 may fill between the displaymodule 210 and the flexible window module 522 at the edge of the mainregion MR. Accordingly, it is possible to prevent contaminant DUST frombeing accumulated on the side surface of the flexible function module221. Further, the flexible window module 522 can be supported by theprotective layer 511.

The outer side surface S-3 d of the flexible window module 522 may be onthe same plane with the outer side surface of the protective layer 511(i.e., the outer side surface of the protective layer 511 at the centerpoint B1 of the bent region BR). The flexible window module 522 coversthe portion of the protective layer 511 that protrudes in theleft-and-right direction due to the thickness of the protective layer511. The flexible window module 522 may completely overlap with orcompletely cover the protective layer 511. More particularly, the outerperiphery of the flexible window module 522 may be in line with theouter periphery of the protective layer 511. Accordingly, the protectivelayer 511 can be protected from an impact at the outer periphery, andthe display device 100_1 can be mounted easily.

Referring to FIG. 6, the display device 100_2 is substantially differentfrom the display device 100 of FIG. 4 in that the display device 100_2further includes a height-compensating layer 660.

The height-compensating layer 660 may be disposed between the flexiblewindow module 222 and the protective layer 411. The height-compensatinglayer 660 may overlap the main region MR of the display module 210 (orthe protective layer 411 in the main region MR of the display module210). Further, the height-compensating layer 660 may overlap a side ofthe lower flexible module 230. The inner side surface of theheight-compensating layer 660 may coincide with the inner side surfaceof the protective layer 411. The height-compensating layer 660 may bespaced apart from the flexible function module 221 in the left-and-rightdirection by a predetermined gap GAP. The predetermined gap GAP may besubstantially zero. Then, the inner side surface of theheight-compensating layer 660 may be in contact with the outer sidesurface (i.e., the side end) S-2 d of the flexible function module 221.

The sum of the thickness of the height-compensating layer 660 and thethickness of the protective layer 411 may be substantially equal to thetotal thickness of the flexible function module 221 and the first andsecond upper double-sided adhesive layers NAD1 and NAD2. In this case,the height-compensating layer 660 may be used to fill between thedisplay module 210 (or the protective layer 411) and the flexible windowmodule 222 at the edge of the main region MR. Accordingly, it ispossible to prevent contaminant DUST from being accumulated on the sidesurface of the flexible function module 221. Further, the flexiblewindow module 222 can be supported by the height-compensating layer 660.

Referring to FIG. 7, a display device 100_3 is substantially differentfrom the display device 100_2 of FIG. 6 in that the display device 100_3further includes a height-compensating layer 760.

The height-compensating layer 760 may be substantially identical to orsubstantially similar to the height-compensating layer 660 describedabove with reference to FIG. 6. In particular, the thickness, the length(i.e., the length in the left-and-right direction), and the position inthe left-and-right direction of the height-compensating layer 760 (i.e.,the position at which it overlaps with the display module 210) may besubstantially the same as those of the height-compensating layer 660shown in FIG. 6, respectively. Therefore, repeated descriptions of theidentical elements will be omitted to avoid redundancy.

The height-compensating layer 760 may be disposed on the display module210.

The protective layer 711, similarly to the protective layer 411described above with reference to FIG. 4, may be disposed in the bentregion BR and the sub region SR, and may be disposed over theheight-compensating layer 760. Specifically, the protective layer 711may be disposed between the height-compensating layer 760 and theflexible window module 222 in the main region MR of the display module210. In particular, the height-compensating layer 760 may be disposedbetween the display module 210 and the protective layer 711.

The inner side surface of the height-compensating layer 760 may be inline with the inner side surface of the protective film 711. Theheight-compensating layer 760 may be spaced apart from the flexiblefunction module 221 in the left-and-right direction by a predeterminedgap GAP. The predetermined gap GAP may be substantially zero.

The sum of the thickness of the height-compensating layer 760 and thethickness of the protective layer 711 may be substantially equal to thetotal thickness of the flexible function module 221 and the first andsecond upper double-sided adhesive layers NAD1 and NAD2. Accordingly, itis possible to prevent contaminant DUST from being accumulated on theside surface of the flexible function module 221. Further, the flexiblewindow module 522 can be supported by the protective layer 711

Referring to FIG. 8, a display device 100_4 is substantially differentfrom the display device 100_1 of FIG. 5 in that the display device 100-4includes a protective layer 811 and a height-compensating layer 860.

The height-compensating layer 860 may be disposed between the displaymodule 210 and the flexible window module 522. The height-compensatinglayer 860 may overlap with the main region MR of the display module 210.The height-compensating layer 860 may be spaced apart from the flexiblefunction module 221 in the left-and-right direction by a first gap GAP1.The first gap GAP1 may be substantially zero.

The thickness of the height-compensating layer 860 may be substantiallyequal to the total thickness of the flexible function module 221 and thefirst and second upper double-sided adhesive layers NAD1 and NAD2.

The protective layer 811, similarly to the protective layer 511described above with reference to FIG. 5, may be interposed between theflexible window module 522 and the display module 210. The protectivelayer 811 may be spaced apart from the height-compensating layer 860 bya second gap GAP2 in the left-and-right direction. The second gap GAP2may be substantially zero.

The thickness of the protective layer 811 may be substantially equal tothe total thickness of the flexible function module 221 and the firstand second upper double-sided adhesive layers NAD1 and NAD2.

In this case, the height-compensating layer 860 and the protective layer811 may be used to fill between the display module 210 and the flexiblewindow module 222 at the edge of the main region MR. Accordingly, it ispossible to prevent contaminant DUST from being accumulated on the sidesurface of the flexible function module 221. Further, the flexiblewindow module 522 can be supported by the height-compensating layer 860and the protective layer 811.

Referring to FIG. 9, a display device 100_5 is substantially differentfrom the display device 100_4 of FIG. 8 in that the display device 100_5includes a protective layer 911 and a height-compensating layer 960.

The height-compensating layer 960 may be substantially identical to orsubstantially similar to the height-compensating layer 860 describedabove with reference to FIG. 8. Therefore, repeated descriptions of theidentical elements will be omitted to avoid redundancy. The length ofthe height-compensating layer 960 in the left-and-right direction may berelatively greater than the length of the height-compensating layer 860.However, the inventive concepts are not limited thereto. For example,the length of the height-compensating layer 960 may be substantiallyequal to or relatively less than the length of the height-compensatinglayer 860.

The protective layer 911 may be disposed on the display module 210 (orthe bent region BR and the sub region SR of the display module 210), andmay be adjacent to or spaced from a flexible function module 221. Thethickness of the protective layer 911 may be substantially equal to thethickness of the protective layer 411 described above with reference toFIG. 4.

The height-compensating layer 960 may be used to fill between thedisplay module 210 and the flexible window module 522 at the edge of themain region MR.

Referring to FIG. 10, a display device 100_6 is substantially differentfrom the display device 100 of FIG. 4 in that the display device 100_6includes an upper flexible module 1020.

The upper flexible module 1020 may include a flexible function module1021.

The flexible function module 1021 may be disposed on the display module210 up to the edge of the main region MR of the display module 210. Inthis case, the outer side surface S-2 d of the flexible function module1021 may protrude outward (e.g., right side) from the outer side surface(i.e., the side end) S-4 d of the lower flexible module 230.

The flexible function module 1021 may be used to fill between thedisplay module 210 and the flexible window module 222 at the edge of themain region MR. Accordingly, the flexible function module 1021 maysupport the flexible window module 222. In addition, even if foreignmatter is accumulated on the side surface of the flexible functionmodule 221, the location where the foreign matter is accumulated isrelatively distant from the display area DPA of the display module 210,so that the influence of the foreign matter on the display module 210may be reduced.

Referring to FIG. 11, a display device 100_7 is substantially differentfrom the display device 100_6 of FIG. 10 in that the display device100_7 includes a height-compensating layer 1160 and a protective layer1111.

Similarly to the height-compensating layer 760 described above withreference to FIG. 7, the height-compensating layer 1160 may be disposedon the display module 210.

The protective layer 1111, similarly to the protective layer 711described above with reference to FIG. 7, may be disposed in the bentregion BR and the sub region SR and may be disposed over theheight-compensating layer 1160. In particular, the height-compensatinglayer 1160 may be disposed between the display module 210 and theprotective layer 1111.

The sum of the thickness of the height-compensating layer 1160 and thethickness of the protective layer 1111 may be substantially equal to thetotal thickness of the flexible function module 221 and the first andsecond upper double-sided adhesive layers NAD1 and NAD2. Accordingly,due to the height-compensating layer 1160, the protective layer 1111,and the flexible function module 1021, it is possible to preventcontaminant DUST from being accumulated on the side surface of theflexible function module 1021. Further, the flexible window module 222can be supported by the height-compensating layer 1160, the protectivelayer 1111, and the flexible function module 1021.

Referring to FIG. 12, a display device 100_8 is substantially differentfrom the display device 100_6 of FIG. 10 in that the display device100_8 further includes a height-compensating layer 1260.

The height-compensating layer 1260 may be disposed between the flexiblewindow module 222 and the protective layer 911. The height-compensatinglayer 1260 may overlap the main region MR of the display module 210 (orthe protective layer 911 in the main region MR of the display module210). The inner side surface of the height-compensating layer 1260 maybe in line with the inner side surface of the protective layer 911. Theheight-compensating layer 1260 may be adjacent to the flexible functionmodule 1021 in the left-and-right direction.

The sum of the thickness H2 of the protective layer 911 and thethickness H3 of the height-compensating layer 1260 may be substantiallyequal to the total thickness H1 of the flexible function module 1021 andthe first and second upper double-sided adhesive layers NAD1 and NAD2.The height-compensating layer 1260 may be used to fill between thedisplay module 210 (or the protective layer 911) and the flexible windowmodule 222 at the edge of the main region MR.

Referring to FIG. 13, a display device 100_9 is substantially differentfrom the display device 100_1 of FIG. 5 in that the display device 100_9includes a protective layer 1311 and an upper flexible module 1320.

The upper flexible module 1320 includes a flexible function module 1021.The flexible function module 1021 may be substantially identical to orsubstantially similar to the flexible function module 1021 describedabove with reference to FIG. 10. Further, the protective layer 1311 maybe substantially identical to or substantially similar to the protectivelayer 511 described above with reference to FIG. 5. Therefore, repeateddescriptions of the substantially identical elements will be omitted toavoid redundancy.

The protective layer 1311 may be disposed between the flexible windowmodule 1322 and the display module 210 and may be spaced apart from oradjacent to the flexible function module 1021 by a predetermined gap GAPin the left-and-right direction.

The thickness of the protective layer 1311 may be substantially equal tothe total thickness of the flexible function module 1021 and the firstand second upper double-sided adhesive layers NAD1 and NAD2.

The outer side surface S-3 d of the flexible window module 1322 may bein line with the outer side surface of the protective layer 1311 (i.e.,the outer side surface at the center point B1 of the bent region BR).

The protective layer 1311 (and the flexible function module 1021) may beused to fill between the display module 210 and the flexible windowmodule 1322 at the edge of the main region MR. Further, the flexiblewindow module 1322 can be supported by the protective layer 1311 and theflexible function module 1021.

Referring to FIG. 14, a display device 100_10 is substantially differentfrom the display device 100_6 of FIG. 10 in that the display device100_10 includes a height-compensating layer 1460 and a protective layer1411.

The height-compensating layer 1460 may be substantially identical to orsubstantially similar to the height-compensating layer 860 describedabove with reference to FIG. 8. Therefore, repeated descriptions of theidentical elements will be omitted to avoid redundancy. The length ofthe height-compensating layer 1460 in the left-and-right direction maybe relatively greater than the length of the height-compensating layer860. However, the inventive concepts are not limited thereto. Forexample, the length of the height-compensating layer 1460 may besubstantially equal to or relatively less than the length of theheight-compensating layer 860.

More specifically, the height-compensating layer 1460 may be disposedbetween the display module 210 and the flexible window module 222 at theedge of the main region MR of the display module 210. Theheight-compensating layer 1460 may be adjacent to or spaced apart fromthe flexible function module 1021 in the left-and-right direction by apredetermined gap.

The thickness of the height-compensating layer 1460 may be substantiallyequal to the total thickness of the flexible function module 1021 andthe first and second upper double-sided adhesive layers NAD1 and NAD2.

The protective layer 1411 may be disposed on the display module 210 (orthe bent region BR and the sub region SR of the display module 210) andmay be adjacent to or spaced from the flexible function module 1021. Thethickness H2 of the protective layer 1411 may be relatively less thanthe thickness H1 of the height-compensating layer 1460 and may besubstantially equal to the thickness of the protective layer 911described with reference to FIG. 10.

Referring to FIG. 15, a display device 100_11 is substantially differentfrom the display device 100_10 of FIG. 14 in that the display device100_11 includes a protective layer 1511 and an upper flexible module1520.

The protective layer 1511 may be disposed similarly to the protectivelayer 1411 described above with reference to FIG. 14, and the thicknessof the protective layer 1511 may be substantially equal to the thicknessH1 of the height-compensating layer 1460.

The upper flexible module 1520 includes a flexible window module 1522.The flexible window module 1522 may be substantially identical to orsubstantially similar to the flexible window module 222 shown in FIG.14. The outer side surface S-3 d of the flexible window module 1522 maybe in line with the outer side surface of the protective layer 1511 atthe center point B1.

FIGS. 16 to 20 are cross-sectional views of display devices according toexemplary embodiments.

Referring to FIG. 16, a display device 100_12 is substantially differentfrom the display device 100 of FIG. 2 in that the display device 100_12includes an upper flexible module 1620.

The upper flexible module 1620 may further include a solid glass layer1623 (or a solidified glass layer), as compared to the upper flexiblemodule 220 described above with reference to FIG. 2.

The solid glass layer 1623 may be disposed or formed on the flexiblewindow module 222. For example, the solid glass layer 1623 may be formedby thinly depositing a glass precursor on a flexible window module 222,which is then melted and solidified by cooling. As another example,after a preliminary layer is formed with a precursor on a separatesubstrate, the preliminary layer is heated to be melt. Then, the meltedpreliminary layer is cooled again to be solidified as a separate solidglass layer (e.g., the solid glass layer 1623 in the form of film).Subsequently, the separate solid glass layer 1623 may be attached on theflexible window module 222 via a lamination process.

The solid glass layer 1623 may include a material that has a low glasstransition temperature (Tg) and also has a low liquidus temperature(LLT).

For example, the solid glass layer 1623 may include a material having aglass transition temperature of 160 degrees or less. Then, the heattreatment temperature for the solid glass layer 1623 (i.e., the heattreatment temperature of the solidification to remove defects (or pores)of the solid glass layer 1623) is relatively low. Therefore, it ispossible to prevent the heat from being transmitted to the displaymodule 210, and to prevent the intermediate layer IL of the displaymodule 210 from being damaged by heat. The heat treatment may be carriedout in a vacuum or an inert atmosphere. By maintaining low-moisture andoxygen-free conditions, it is possible to prevent moisture or oxygenfrom permeating between the thin film encapsulation structure of thedisplay module 210 (i.e., the upper encapsulation multilayer and thelower encapsulation multilayer described above with reference to FIG.2). The material having a low glass transition temperature may contain55 to 75 wt % of stannum (Sn), 4 to 14 wt % of phosphorus (P), 6 to 24wt % of oxygen (O), 4 to 22 wt % of fluorine (F), and 0.5 to 15 wt % oftungsten (W).

As another example, the solid glass layer 1623 may include a materialhaving a liquidus temperature of 1,000° C. or less, 600° C. or less, or400° C. or less. The heat treatment temperature to remove defects (orpores) in a material that has a low liquidus temperature is relativelylow. Therefore, the solid glass layer 1623 without pores can be obtainedat a relatively low temperature (i.e., a temperature at which theintermediate layer IL of the display module 210 is not damaged). Thesolid glass layer 1623 may include, as the material having a lowliquidus temperature, tin fluoride phosphate glass, chalcogenide glass,tellurite glass, borate glass, and phosphate glass (e.g., alkaline zincor tin zinc pyrophosphates). For example, the material having a lowliquidus temperature may include 20 to 85 wt % of stannum (Sn), 2 to 20wt % of phosphorus (P), 10 to 36 wt % of oxygen (O), 10 to 36 wt % offluoro (F), and 0.5 to 5 wt % of niobium (Nb). The sum of the contentsof tin, phosphorus, oxygen and fluorine may be 75% by weight.

The solid glass layer 1623 has a thickness relatively less thanultra-thin glass (UTG), so that it can reduce the folding radius ofcurvature (or the radius of curvature of the foldable region FR, thebending radius of curvature) significantly. For example, by employingthe solid glass layer 1623, the folding radius of curvature can bereduced to 5 mm or less, and even to 4 mm or less.

In addition, by employing the solid glass layer 1623, it is possible toeasily achieve a surface strength as desired by the materialcharacteristics. For example, the surface of the solid glass layer 1623can be chemically treated to a certain depth to increase the surfacestrength. For example, the surface strength of the solid glass layer1623 can be improved by exchanging sodium ions contained in the solidglass layer 1623 with potassium ions (i.e., potassium ions relativelylarger in size than sodium ions) via chemical treatment.

When the display device 100 is completely folded, one end (or the uppersurface of the one end) and the other end (or the upper surface of theother end) of the solid glass layer 1623 may come in contact with eachother. In doing so, an impact may occur between the one end and theother end, such that damage (e.g., a crack) may be created on the topsurface of the display device 100 or the like. Therefore, by employingthe solid glass layer 1623, it is possible to prevent damage (e.g., acrack) to the display device 100 by achieving a relatively high surfacestrength.

On the other hand, the solid glass layer 1623 may be included in thehigh neutral plane control portion (HNPC) to place the neutral plane NPin the display module 210.

Referring to FIG. 17, a display device 100_13 is substantially differentfrom the display device 100_12 of FIG. 16 in that the display device100_13 includes an upper flexible module 1720.

The upper flexible module 1720 may further include a buffer layer 1723as compared to the upper flexible module 1620 shown in FIG. 16. Thesolid glass layer 1724 may be substantially identical to the solid glasslayer 1623 described above with reference to FIG. 16. Therefore,repeated descriptions of the substantially identical elements will beomitted to avoid redundancy.

The buffer layer 1723 may be interposed between the flexible windowmodule 222 and the solid glass layer 1724. The buffer layer 1723 may beincluded in the high neutral plane control portion (HNPC).

The buffer layer 1723 may include an inorganic material such asamorphous silicon (a-Si), silicon nitride (SiN_(x)), and silicon oxide(SiO_(x)). If the flexible window module 222 (or the surface of theflexible window module 222) includes an organic material, the bufferlayer 1723 can increase the adhesion.

After the display module 210, the flexible function module 221, theflexible window module 222 and the like are integrated, the solid glasslayer 1724 may be formed on the buffer layer 1723. When the solid glasslayer 1724 is deposited on the buffer layer 1723 and then melted, thebuffer layer 1723 containing the inorganic material may be used toprevent heat from being transferred to the upper flexible module 1720(or the flexible window module 222) and/or the display module 210.

Although the buffer layer 1723 is described as containing an inorganicmaterial, the inventive concepts are not limited thereto, and the bufferlayer 1723 may include an organic material. Then, the buffer layer 1723may provide a flat surface over the solid glass layer 1724.

Referring to FIG. 18, a display device 100_14 is substantially differentfrom the display device 100_12 of FIG. 16 in that the display device100_14 includes an upper flexible module 1820.

The upper flexible module 1820 may further include a protective layer1824 as compared to the upper flexible module 1620 shown in FIG. 16. Thesolid glass layer 1823 may be substantially identical to the solid glasslayer 1623 described above with reference to FIG. 16, and thus, repeateddescriptions of the substantially identical elements will be omitted toavoid redundancy.

The protective layer 1824 may be disposed on the solid glass layer 1823.The protective layer 1824 may be included in the high neutral planecontrol portion (HNPC).

The protective layer 1824 may include an inorganic material, such asamorphous silicon (a-Si), silicon nitride (SiN_(x)), and silicon oxide(SiO_(x)), similarly to the buffer layer 1723 described above withreference to FIG. 17.

The protective layer 1824 is disposed on the solid glass layer 1823,e.g., at the top of the display device 100_14, so that it is possible toprevent damage to the solid glass layer 1823 while the display device100_14 is folded and unfolded repeatedly.

Referring to FIG. 19, a display device 100_15 is substantially differentfrom the display device 100_13 of FIG. 17 (and the display device 100_14of FIG. 18) in that the display device 100_15 includes an upper flexiblemodule 1920.

The upper flexible module 1920 may include a flexible function module221, a flexible window module 222, a buffer layer 1923, a solid glasslayer 1924, and a protective layer 1925.

The buffer layer 1923, the solid glass layer 1924, and the protectivelayer 1925 may be included in a high neutral plane control portion(HNPC).

The buffer layer 1923 is substantially identical to the buffer layer1723 described above with reference to FIG. 17. The solid glass layer1924 is substantially identical to the solid glass layer 1623 describedabove with reference to FIG. 16. The protective layer 1925 issubstantially identical to the protective layer 1824 described abovewith reference to FIG. 18. Therefore, repeated descriptions of thesubstantially identical elements will be omitted to avoid redundancy.

The adhesion of the solid glass layer 1924 can be increased by thebuffer layer 1923 and the protective layer 1925, and damage can besuppressed.

Referring to FIG. 20, a display device 100_16 is substantially differentfrom the display device 100_14 of FIG. 18 in that the display device100_16 includes an upper flexible module 2020.

The upper flexible module 2020 may include a flexible function module221, a flexible window module 222, a first solid glass layer 2023, anintermediate layer 2024, and a second solid glass layer 2025.

Each of the first solid glass layer 2023 and the second solid glasslayer 2025 may be substantially identical to the solid glass layer 1623described above with reference to FIG. 16. Therefore, repeateddescriptions of the substantially identical elements will be omitted toavoid redundancy. The intermediate layer 2024 may include an inorganicmaterial such as amorphous silicon (a-Si), silicon nitride (SiN_(x)) andsilicon oxide (SiO_(x)) or an organic material, similarly to the bufferlayer 1723 described above with reference to FIG. 17.

The first solid glass layer 2023 may be disposed or formed on theflexible window module 222. The intermediate layer 2024 may be disposedor formed on the first solid glass layer 2023. The second solid glasslayer 2025 may be disposed or formed on the intermediate layer 2024.More particular, the first solid glass layer 2023, the intermediatelayer 2024, and the second solid glass layer 2025 may be stacked on theflexible window module 222 in sequence.

The strength of the surface of the display device 100_16 can beincreased by the first solid glass layer 2023 and the second solid glasslayer 2025. Damage to the first solid glass layer 2023 and the secondsolid glass layer 2025 can be prevented by the intermediate layer 2024.

FIG. 21 is a cross-sectional view of a display device according toanother exemplary embodiment. FIG. 22 is a plan view of a color filterincluded in a display device according to another exemplary embodiment.FIG. 23 is a cross-sectional view taken along line IV-IV′ of FIG. 22.

Referring to FIGS. 21 to 23, a display device 100_17 is substantiallydifferent from the display device 100 of FIG. 2 in that the displaydevice 100_17 includes an upper flexible module 2120.

The upper flexible module 2120 may include a color filter 2121 (or acolor filter layer) instead of the flexible function module 221 (forexample, a polarizing film) shown in FIG. 2.

The color filter 2121 may be disposed between the display module 210 andthe flexible window module 222, and may be attached or coupled with thedisplay module 210 and the flexible window module 222 by first andsecond upper double-sided adhesive layer NAD1 and NAD2.

Similarly to the polarizing filter, the color filter 2121 can preventreflection of external light to thereby improve the visibility of thedisplay device 100_17. By removing a polarizing film that is frequentlydetached while the display device is folded or unfolded repeatedly, itis possible to implement a POL-less display device.

The color filter 2121 may include a flexible polymer material such aspolyimide. Then, the foldability (or ease folding) and transparency ofthe color filter 2121 can be achieved.

On the other hand, the color filter 2121 may be included in the highneutral plane control portion HNPC to place the neutral plane NPpartially formed in the foldable region FR of the display module 210 inthe display module 210.

As shown in FIG. 22, the color filter 2121 may include a red colorfilter CF_R (or a first monochromatic color filter), a green colorfilter CF_G (or a second monochromatic color filter), and a blue colorfilter CF_B (or a third monochromatic color filter). The red colorfilter CF_R, the green color filter CF_G, and the blue color filter CF_Bmay be arranged in a lattice shape.

The red color filter CF_R and the blue color filter CF_B may be arrangedalternately adjacent to each other in the left-and-right direction. Thered color filter CF_R and the blue color filter CF_B may be arrangedalternately adjacent to each other in the up-and-down direction. Thegreen color filter CF_G may be disposed between the red color filterCF_R and the blue color filter CF_B (or between the nearest red colorfilters CF_R and between the nearest blue color filters CF_B). The redcolor filter CF_R, the green color filter CF_G, and the blue colorfilter CF_B may be arranged at equal intervals and spaced apart fromeach other. Specifically, the red color filters CF_R, the green colorfilters CF_G, and the blue color filters CF_B may be repeatedly arrangedin the diagonal direction (or a first direction). The red color filterCF_R, the green color filter CF_G, and blue color filter CF_B next toone another may be arranged in A shape (or A arrangement).

The red color filter CF_R may have a square shape. The corners of thesquare opposed to each other with respect to the center of area may belocated on the same horizontal line or vertical line. Similarly, theblue color filter CF_B may have a square shape and may be disposedbetween the red color filters CF_R in the up-and-down direction and theleft-and-right direction. Each of the corners of the blue color filterCF_B may be adjacent to the respective corners of different red colorfilters CF_R. The length of the sides of the blue color filter CF_B maybe relatively greater than the length of the sides of the red colorfilter CF_R.

The green color filter CF_G may have a rectangular shape or an octagonalshape. The space formed by the red color filter CF_R and the blue colorfilter CF_B may have a rectangular shape, and the green color filterCF_G may have a shape conforming to this space.

As the red, green, and blue color filters CF_R, CF_G and CF_B arearranged in a lattice (or A arrangement), one direction of the latticeof the color filters may be substantially different from the directionin which the folding axis AXIS_F of the display device 100_17 isextended. For example, the first direction in which monochromatic colorfilters are arranged may form an acute angle with the folding axisAXIS_F. As such, defects that would otherwise occur when the directionof the lattice coincides with the folding axis can be reduced.

The display module 210 may include red, green, and blue pixels EL_R,EL_G, and EL_B (or red, green and blue light-emitting elements, first tothird light-emitting elements, first to third electroluminescentlayers). The red, green, and blue pixels EL_R, EL_G, and EL_B may bearranged in a lattice (or A shape) corresponding to the red color filterCF_R, the green color filter CF_G, and the blue color filter CF_B,respectively.

Therefore, it is possible to suppress defects that may otherwise occurwhen one direction of the lattice of the red, green, and blue pixelsEL_R, EL_G, and EL_B coincides with the folding axis. The circuit wiringfor the red, green, and blue pixels EL_R, EL_G, and EL_B may have anarrangement that coincides with the folding axis.

The red pixel EL_R may have a square shape, similarly to the red colorfilter CF_R. The red pixel EL_R may have the same center of area as thered color filter CF_R and may have an area relatively larger than thatof the red color filter CF_R. Similarly, the blue pixel EL_B may havethe same shape as the blue color filter CF_B, may have the same centerof area as the blue color filter CF_B, and may have an area relativelylarger than that of the blue color filter CF_B. The green pixel EL_G mayhave the same shape as the green color filter CF_G, may have the samecenter of area as the green color filter CF_G, and may have an arearelatively larger than that of the green color filter CF_G.

Even if the pixels EL_R, EL_G, and EL_B overlap with one another, onlythe corresponding colors are transmitted by the color filters, so thateach of the pixels EL_R, EL_G, and EL_B may be formed by overlappingwith one another and may have a relatively large area. Accordingly,openings for depositing pixels in order to form each of the pixels EL_R,EL_G, and EL_B (i.e., openings PDL_R, PDL_G, and PDL_B of the pixeldefining layer PDL) may become larger, and the pixel deposition rate canbe improved.

More particularly, the openings PDL_R, PDL_G, and PDL_B of the pixeldefining layer PDL are relatively smaller than the openings of the colorfilters CF_R, CF_G, and CF_B, and the periphery REL, GEL and BEL of thepixels (e.g., the pixels EL_R, EL_G, and EL_B) may be relatively largerthan the openings of the color filters. Accordingly, the processingmargin for pixel deposition can be increased until the different pixelsEL_R, EL_G, and EL_B overlap with one another.

Accordingly, the red pixel EL_R may overlap with the green pixel EL_G ina first overlapping area A, and the green pixel EL_G may overlap withthe blue pixel EL_B in a second overlapping area B. In addition, in athird overlapping area C, the green pixel EL_G, the blue pixel EL_B, andthe green color filter CF_G may overlap with one another. In theoverlapping areas A and B, a material capable of transferring (orcarrying) charges provided from the lower electrode (LE in FIG. 3)between overlapping pixels may be interposed.

Referring to FIG. 23, as described above with reference to FIG. 3, thelower electrodes LE may be disposed on the fifth inorganic layer 325 (orthe planarization layer), and the pixel defining layers PDL may beformed to partially overlap with the lower electrodes LE. The portionsof the lower electrodes LE exposed by the pixel defining layers PDL maybe the openings PDL_R, PDL_G, and PDL_B of the pixel defining layer. Thered pixel EL_R, the green pixel EL_G, and the blue pixel EL_B may beformed in the respective openings of the pixel defining layer PDL. Forthe resonance effect, the pixels may have substantially differentheights R1, G1, and B1 (or substantially different thicknesses) from thelower electrodes LE in proportion to the length of the wavelength ofeach color, where R1>G1>B1. The upper electrode UE may be disposed onthe pixels. The color filters 2121 may be disposed on the upperelectrode UE.

The color filters 2121 may include red, green, and blue color filtersCF_R, CF_G, and CF_B using a transparent film TP as a substrate. Thethickness of the center of each of the color filters CF_R, CF_G, andCF_B may be relatively greater than the thickness at the edge, inconsideration of the manufacturing method (for example, pigmentdispersion method) of the color filter 2121, side visibility, etc. Anupper planarization layer DFL and a lower planarization layer LFL aredisposed on the upper and lower surfaces of the color filters CF_R, CF_Gand CF_B, respectively, to flatten the color filters CF_R, CF_G and CF_Bhaving substantially different levels. The upper planarization layer orthe lower planarization layer may be made of a biphenyl-based epoxymaterial.

The distances R2, G2, and B2 from the pixels to the color filters may besubstantially different from one another, in consideration of theresonance effect, where R2<G2<B2.

More specifically, the display device 100_17 may include: a lowerelectrode layer including a first lower electrode (e.g., the lowerelectrode LE corresponding to the green pixel EL_G) having first andsecond areas (i.e., the area not overlapping with the pixel defininglayer PDL and the area overlapping with it), and a second lowerelectrode (e.g., the lower electrode LE corresponding to the blue pixelEL_B) having third and fourth areas; the pixel defining layer PDLdisposed on the lower electrode layer and not covering the first andthird areas while covering the second and fourth areas; a firstelectroluminescent layer (e.g., the light-emitting element of the greenpixel EL_G) disposed on the pixel defining layer PDL and the first areaof the first lower electrode, having an outline substantially (e.g.,completely) surrounding the outline of the first area when viewed fromthe top, and having an area relatively larger than the first area; asecond electroluminescent layer (e.g., the light-emitting element of theblue pixel EL_B) disposed on the pixel defining layer PDL and the thirdarea, having an outline substantially (e.g., completely) surrounding theoutline of the third area when viewed from the top, and having an arearelatively larger than the third area; an upper electrode UE disposed onthe first and second electroluminescent layers, having an outlinesubstantially (e.g., completely) surrounding the outlines of the firstand second electroluminescent layers when viewed from the top, andhaving an area relatively larger than the first and secondelectroluminescent layers; and a color filter layer (e.g., the colorfilter 2121) having a first color filter (e.g., the green color filterCF_G) disposed on the upper electrode UE and having a first colorfiltering area having an outline located between the outline of thefirst area and the outline of the first electroluminescent layer whenviewed from the top, and a second color filter (e.g., the blue colorfilter CF_B) disposed on the upper electrode UE and having a secondcolor filtering area having an outline located between the outline ofthe third area and the outline of the second electroluminescent layerwhen viewed from the top. The first and second electroluminescent layersmay overlap with each other. The first electroluminescent layer emitslight of a first wavelength (e.g., green light), and the secondelectroluminescent layer emits light of a second wavelength (e.g., bluelight) relatively shorter than the first wavelength. The firstelectroluminescent layer may be disposed on the secondelectroluminescent layer. Further, the second electroluminescent layermay overlap with a first color filtering area (e.g., the light-emittingelement of the blue pixel EL_B may overlap with the green color filterCF_G in the third overlapping area C).

As described above, the display device 100_17 includes the color filter2121 instead of the polarizing film, thereby preventing reflection ofexternal light and improving visibility. In addition, since the colorfilters and the respective pixels (i.e., the pixels included in thedisplay module 210) are arranged in a lattice (or A shape), and onedirection of the lattice is not parallel or does not coincide with thefolding axis, it is possible to minimize defects that may otherwisewould occur when the lattice direction coincides with the folding axis.Further, even if the pixels of different colors overlap with oneanother, only the light of the corresponding color is transmittedthrough each of the color filters. As such, different pixels can overlapwith one another, thereby improving the processing margin of the pixeldeposition and the deposition rate.

FIGS. 24 and 25 are cross-sectional views of display devices accordingto exemplary embodiments.

Referring to FIG. 24, a color filter 2321 is substantially differentfrom the color filter 2121 of FIG. 23 in that the color filter 2321further includes red, green, and blue color filters CF_R, CF_G, and CF_Boverlapping with one another and a black matrix BM.

In the areas where the pixels overlap with one another, the red, green,and blue color filters CF_R, CF_G, and CF_B may overlap with other colorfilters. For example, the red color filter CF_R may overlap with thegreen color filter CF_G in the first overlapping area A, and the greencolor filter CF_G may overlap with the blue color filter CF_B in thesecond overlapping area B.

The black matrix BM may be disposed in the area where the red, green,and blue color filters CF_R, CF_G, and CF_B overlap with one another(e.g., the first overlapping area A and the second overlapping area B).The black matrix BM may be used to separate red, green, and blue lightfrom one another and may block light therebetween.

Referring to FIG. 25, a color filter 2521 is substantially differentfrom the color filter 2121 of FIG. 23 in that the color filter 2521further includes a black matrix BM.

The black matrix BM may be disposed between the red, green, and bluecolor filters CF_R, CF_G, and CF_B described above with reference toFIG. 22. The black matrix BM may be thicker at the center than at theedge.

It is to be noted that the openings RCF, GCF, and BCF of the colorfilters CF_R, CF_G, and CF_B may be formed or defined by the blackmatrix BM, substantially differently from the openings of the colorfilters shown in FIG. 23. As a result, there may be no secondoverlapping area B.

As described above, the color filter 2521 may include a black matrix BM,such that the overlapping area (e.g., the second overlapping area B) canbe removed.

FIG. 26 is a cross-sectional view of a display device according to yetanother exemplary embodiment. FIG. 27 is a cross-sectional view of adisplay module included in the display device according to an exemplaryembodiment.

Referring to FIGS. 26 and 27, a display device 100_18 is substantiallydifferent from the display device 100 of FIG. 4 in that the displaydevice 100_18 includes a display module 2610.

The display module 2610 may include substantially different materials ina first area A1 and a second area A2.

As shown in FIGS. 26 and 27, the first area A1 of the display module2610 may include a first polymer layer 2711 of a first repeated subunitorganic compound (e.g., monomer), while the second area A2 of thedisplay module 2610 may include a second polymer layer 2712 of a secondrepeated subunit organic compound (e.g., monomer). The first polymerlayer 2711 may be disposed on the lower surface of the display module2610 in the sub region SR, while the second polymer layer 2712 may bedisposed on the lower surface of the display module 2610 in the mainregion MR (e.g., when the display module 2610 is not bent).

The first polymer layer 2711 may include polyethylene terephthalate(PET) or an acrylic resin. For example, when the first polymer layer2711 is made of polyethylene terephthalate (PET), the first repeatedsubunit organic compound may be bis(2-hydroxyethyl) terephthalate.

The second polymer layer 2712 may be a colored polyimide (PI).

When the second polymer layer 2712 is extended to the first polymerlayer 2711 in the display module 2610 (e.g., when the second polymerlayer 2712 is disposed in the first area A1), a carbon material may begenerated from the colored PI during a laser processing to shape the padunit (e.g., the panel pad unit for coupling with the circuit board 422),which may be accumulated on the near side walls. In addition, foreignmatter may be generated when the pads included in the pad unit arethermally compressed. Furthermore, since the colored PI has a lowvisible light transmittance than PET, it may act as an inhibiting factorduring the process of thermo-compression. In addition, when the secondpolymer layer 2712 is extended to the first polymer layer 2711 in thedisplay module 2610 (e.g., when the second polymer layer 2712 isdisposed in the first area A1), since the reliability of PET underhigh-temperature and high-humidity is relatively less than that of thecolored PI, it may be difficult to obtain reliability of the organiclight-emitting diode (OLED) formed on the display module 2610 under hightemperature and high humidity. Therefore, the first and second polymerlayers 2711 and 2712 may be separated from each other, and PET may beused as the first polymer layer 2711 and the colored PI may be used asthe second polymer layer 2712.

The flexible window module 222 may include a third polymer layer of athird repeated subunit organic compound (e.g., monomer). The thirdpolymer layer may contain a transparent PI. When the second polymerlayer 2712 is a colored PI, the second repeated subunit organic compoundand the third repeated subunit organic compound may include the sameimide series.

Although the third polymer layer may include PI due to its strength, thePI generally may have a yellowish color. As such, the PI having a colormay not be appropriate for the window. Thus, by reducing the aromaticring density of PI, the third polymer layer may be made of transparentPI. However, the thermal and mechanical properties, such as the ultimatetensile strength, initial tensile modulus, elongation at break, andglass transition temperature may be somewhat reduced.

When the first polymer layer 2711 is made of PET or an acrylic resin,the second polymer layer 2712 may include the colored PI and the thirdpolymer layer may include the transparent PI. In this manner, the firstpolymer layer 2711, the second polymer layer 2712, and the third polymerlayer may have the following relationship in thermal and mechanicalproperties.

The second polymer layer 2712 may have an ultimate tensile strength(MPa) relatively greater than that of the first polymer layer 2711. Thethird polymer layer may have an ultimate tensile strength relativelygreater than that of the first polymer layer 2711. The second polymerlayer 2712 may have the ultimate tensile strength relatively greaterthan that of the third polymer layer.

The second polymer layer 2712 may have an initial tensile modulus (GPa)relatively greater than that of the first polymer layer 2711. The thirdpolymer layer may have an initial tensile modulus relatively greaterthan that of the first polymer layer 2711. The second polymer layer 2712may have an initial tensile modulus relatively greater than that of thethird polymer layer.

The second polymer layer 2712 may have an elongation percent at break(%) relatively greater than that of the first polymer layer 2711. Thethird polymer layer may have an elongation percentage at breakrelatively greater than that of the first polymer layer 2711. The secondpolymer layer 2712 may have an elongation percentage at break relativelygreater than that of the third polymer layer.

The second polymer layer 2712 may have an O₂ transmission rate(cc/m²/day) relatively less than that of the first polymer layer 2711.The third polymer layer may have an O₂ transmission rate relatively lessthan that of the first polymer layer 2711. The second polymer layer 2712may have an O₂ transmission rate relatively less than that of the thirdpolymer layer.

The second polymer layer 2712 may have a glass transition temperature(Tg, ° C.) relatively greater than that of the first polymer layer 2711.The third polymer layer may have a glass transition temperaturerelatively greater than that of the first polymer layer 2711. The secondpolymer layer 2712 may have a glass transition temperature relativelygreater than that of the third polymer layer.

The second polymer layer 2712 may have a visible light transmittancerelatively greater than that of the first polymer layer 2711 (e.g.,light in the range of 380 to 780 nm). The third polymer layer may have avisible light transmittance relatively greater than that of the secondpolymer layer 2712.

The second polymer layer 2712 may have a yellow index (YI) relativelygreater than that of the first polymer layer 2711. The second polymerlayer 2712 may have a yellow index (YI) relatively greater than that ofthe third polymer layer.

The second polymer layer 2712 may have an aromatic ring densityrelatively greater than that of the first polymer layer 2711. The thirdpolymer layer may have an aromatic ring density relatively greater thanthat of the first polymer layer 2711. The second polymer layer 2712 mayhave an aromatic ring density relatively greater than that of the thirdpolymer layer.

As described above, the display module 2610 includes the colored PIdisposed adjacent to the main region MR, and the PET disposed adjacentto the sub region SR, so that the quality of the device can be improved.

FIG. 28 is a cross-sectional view of a display device according to yetanother exemplary embodiment.

Referring to FIG. 28, a display device 100_19 is substantially differentfrom the display device 100_18 of FIG. 26 in that the display device100_19 further includes a spacer layer 2881.

The spacer layer 2881 may be disposed between the second plate 242 (orthe rigid layer 240) and the sub region SR of the display module 2610.The spacer layer 2881 may prevent breakage of the bent region BR due toerroneous setting of the bending radius of curvature R of the displaymodule 2610 (e.g., if the bending radius of curvature R is set to be toosmall).

The spacer layer 2881 may be attached to the display module 2610 and therigid layer 240 (e.g., second plate 242) by double-sided adhesive layers2882 and 2883, respectively.

FIGS. 29 and 30 are views for illustrating a process of fabricating adisplay device according to another exemplary embodiment.

Referring to FIGS. 29 and 30, a first structure STR1 may be prepared.The first structure STR1 may include a lower flexible film 2812 (or afirst flexible member), a first release film RF1, and a lower releasefilm RF2. The lower flexible film 2812 may be the second organicflexible layer 312 as shown in FIG. 3. The lower flexible film 2812 mayhave a first height H11. The first release film RF1 may have a firstrelease force and may be attached on the lower flexible film 2812. Thelower release film RF2 may have a second release force and may beattached under the lower flexible film 2812. The second release forcemay be relatively greater than the first release force. For example, thesecond release force may be “n” times the first release force, where “n”is a real number relatively greater than about one. For example, thefirst release force may be approximately 6 to 9 gf/in, and the secondrelease force may be approximately 26 to 38 gf/in. More particularly,when the second release force is relatively greater than the firstrelease force, the lower release film RF2 may not be detached when thefirst release film RF1 is detached.

A preliminary panel 2811 may be prepared. The preliminary panel 2811 mayinclude elements of the display module 210 described above withreference to FIG. 3, except for the second organic flexible layer 312and the double-sided adhesive layer 313. The third release film RF3 maybe attached on the upper surface of the preliminary panel 2811, and thefourth release film RF4 may be attached under the lower surface of thepreliminary panel 2811.

Subsequently, the first release film RF1 may be detached from the uppersurface of the lower flexible film 2812. The lower release film RF2 maynot be detached from the lower surface of the lower flexible film 2812.

At the same time, the fourth release film RF4 may be detached from thelower surface of the preliminary panel 2811. The third release film RF3may not be detached from the upper surface of the preliminary panel2811.

The preliminary panel 2811 may be attached on the lower flexible film2812 by the double-sided adhesive layer 313.

Subsequently, the third release film RF3 may be detached or removed fromthe upper surface of the preliminary panel 2811, and the flexiblefunction module 221 and the flexible window module 222 may be formed onthe upper surface of the preliminary panel 2811. For example, theflexible function module 221 may be attached to the upper surface of thepreliminary panel 2811 by the second upper double-sided adhesive layerNAD2, and the flexible window module 222 may be attached to the uppersurface of the flexible function module 221 by the first upperdouble-sided adhesive layer NAD1. A fifth release film RF5 may beattached to the upper surface of the flexible window module 222.

In particular, the preliminary panel 2811, the second upper double-sidedadhesive layer NAD2, the flexible function module 221, the first upperdouble-sided adhesive layer NAD1, and the flexible window module 222 maybe sequentially stacked on the lower flexible film 2812, such that thesecond structure STR2 may be formed. The fifth release film RF5 may havea third release force. The third release force may be relatively lessthan the second release force (i.e., the release force of the lowerrelease film RF2). For example, the second release force may be “m”times the third release force, where “m” is a real number relativelygreater than 3. For example, although the release force of the fifthrelease film RF5 cannot be sufficiently increased because the uppersurface of the flexible window module 222 is subjected toanti-fingerprint process, the release force of the fifth release filmRF5 may be in the range of 10 to 26 gf/in to prevent the fifth releasefilm RF5 from being detached while the lower release film RF2 isdetached.

The adhesive force of the double-sided adhesive layer 313 to the lowerflexible film 2812 and the adhesive force of the double-sided adhesivelayer 313 to the second structure STR2 may be relatively greater thanthe second release force and the third release force.

Subsequently, the lower release film RF2 may be detached or removed fromthe lower surface of the lower flexible film 2812. The fifth releasefilm RF5 may not be detached from the upper surface of the flexiblewindow module 222 (or the second structure STR2).

A lower flexible module 230 and a plate 240 (i.e., a rigid layer) may beattached under the lower flexible film 2812. The lower flexible module230 and the plate 240 are already coupled with each other by the fourthdouble-sided adhesive layer NAD4, and may be attached under the lowerflexible film 2812 by the lower double-sided adhesive layer NAD3.

The adhesive force of the lower double-sided adhesive layer NAD3 may berelatively larger than the first to third release forces. Therefore, thelower double-sided adhesive layer NAD3 may not be detached when therelease films (e.g., the second release film RF2 and the third releasefilm RF3) are removed. Similarly, the adhesive strength of the first andsecond upper double-sided adhesive layers NAD1 and NAD2 may berelatively greater than the first to third release forces.

In an exemplary embodiment, the first release force of the first releasefilm RF1 may be approximately 6.5 to 7.5 gf/in, the second release forceof the lower release film RF2 may be 32.5 to 33.5 gf/in, and the thirdrelease force of the fifth release film RF5 may be 19.5 to 20.5 gf/in.According to an exemplary embodiment, “n” may be relatively greater than“m”. More specifically, “n” may range from 4 to 5, and “m” may rangefrom 1.5 to 2.

According to an exemplary embodiment, a foldable display device includesa first polymer layer including a first repeated subunit organiccompound and a second polymer layer including a second repeated subunitorganic compound, to improve thermal and mechanical properties and thequality of the device.

According to another exemplary embodiment, a method of manufacturing afoldable display device can prevent the deterioration of the quality ofthe display device by manufacturing the display device in considerationof the release force of a release film having a flexible film attachedthereto.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of theappended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. A foldable display device, comprising: a lowermodule having a first side end disposed in a first side area of thefoldable display device; a double-sided adhesive layer on the lowermodule; a display module on the double-sided adhesive layer, the displaymodule including, as one body: a main region including a display areadisposed over the lower module, the main region having a first side enddisposed in the first side area, the display area including an emissiveunit having a first electrode, a second electrode, and an emission layerbetween the first and second electrodes, the display area having a firstside end disposed in the first side area; a sub region disposed underthe lower module and overlapping the main region, the sub region havinga first side end disposed in the first side area; and a bent regionbeing disposed in the first side area and being between the first sideend of the main region and the first side end of the sub region suchthat the bent region is bent between the first side end of the mainregion and the first side end of the sub region, the bent region havingan outer surface between an upper surface of the main region and a lowersurface of the sub region, and an inner surface between a lower surfaceof the main region and an upper surface of the sub region; a functionalmodule disposed on the main region, the functional module having a firstside end disposed in the first side area; and a window module disposedon the functional module, the window module having a first side enddisposed in the first side area, wherein the display module includes alower inorganic encapsulation structure and an upper encapsulationstructure, the emissive unit being located between the lower inorganicencapsulation structure and the upper encapsulation structure, both ofthe upper encapsulation structure and the window module are flexible,the first side end of the main region is disposed outwardly away fromthe first side end of the display area in plan view, and the first sideend of the main region is not disposed inwardly away from the first sideend of the lower module in plan view, the upper encapsulation structurehas a lower surface comprising only at least one inorganic material, thelower inorganic encapsulation structure and the upper encapsulationstructure directly contacting each other to encapsulate the emissiveunit, the foldable display device comprises a height-compensating layerstructure having at least a portion disposed on the main region,disposed outwardly away from the first side end of the functional modulein plan view, and disposed inwardly away from the first side end of themain region in plan view, the height-compensating layer structure has,between the main region and the window module, a height substantiallythe same as a distance between the main region and the window module,and the height-compensating layer structure supports the window module,which is flexible, to prevent the window module from bending, theheight-compensating layer structure preventing an accumulation ofcontaminants near the first side end of the functional module.
 2. Thefoldable display device of claim 1, wherein the foldable display devicehas a space between the height-compensating layer structure, the mainregion, and the first side end of the functional module, the spacehaving a closed shape in cross-sectional view.
 3. The foldable displaydevice of claim 2, wherein the foldable display device comprises abending protection layer disposed on the outer surface of the bentregion, the bending protection layer has a first portion included in theat least the portion of the height-compensating layer structure, and thefirst portion of the bending protection layer is spaced apart from thefirst side end of the functional module.
 4. The foldable display deviceof claim 3, wherein the height-compensating layer structure comprises anadditional layer on the first portion of the bending protection layer.5. The foldable display device of claim 2, wherein the functional moduleprovides at least one selected from the group of a polarizationfunction, a color filtering function, a color conversion function, and atouch sensing function.
 6. The foldable display device of claim 2,wherein the first side end of the functional module is disposed inwardlyaway from the first side end of the lower module in plan view, the lowermodule has a portion disposed inwardly away from the first side end ofthe lower module in plan view and disposed outwardly away from the firstside end of the functional module in plan view, a portion of the mainregion is disposed over the portion of the lower module to be supportedby the portion of the lower module, and the at least the portion of theheight-compensating layer structure is disposed over the portion of themain region to be supported by the portion of the main region.
 7. Thefoldable display device of claim 2, wherein the contaminants are carboncontaminants generated when a laser ablation process is employed to forman outer periphery of at least one selected from the group of thedisplay module and the window module.
 8. The foldable display device ofclaim 2, wherein the foldable display device comprises: a base layerhaving first and second rigid plate portions between which a foldableregion of the foldable display device is located, the base layer beingdisposed under the lower module; and a circuit board located under thebase layer, and the sub region is disposed between the base layer andthe circuit board, the circuit board being attached to the sub regionsuch that the circuit board is electrically connected to the sub region.9. The foldable display device of claim 1, wherein the functional moduleprovides at least one selected from the group of a polarizationfunction, a color filtering function, a color conversion function, and atouch sensing function.
 10. The foldable display device of claim 1,wherein the first side end of the functional module is disposed inwardlyaway from the first side end of the lower module in plan view, the lowermodule has a portion disposed inwardly away from the first side end ofthe lower module in plan view and disposed outwardly away from the firstside end of the functional module in plan view, ii a portion of the mainregion is disposed over the portion of the lower module to be supportedby the portion of the lower module, and the at least the portion of theheight-compensating layer structure is disposed over the portion of themain region to be supported by the portion of the main region.
 11. Thefoldable display device of claim 1, wherein the contaminants are carboncontaminants generated when a laser ablation process is employed to forman outer periphery of at least one selected from the group of thedisplay module and the window module.
 12. The foldable display device ofclaim 1, wherein the foldable display device comprises: a base layerhaving first and second rigid plate portions between which a foldableregion of the foldable display device is located, the base layer beingdisposed under the lower module; and a circuit board located under thebase layer, and the sub region is disposed between the base layer andthe circuit board, the circuit board being attached to the sub regionsuch that the circuit board is electrically connected to the sub region.13. A foldable display device, comprising: a lower module having a firstside end disposed in a first side area of the foldable display device; adouble-sided adhesive layer on the lower module; a display module on thedouble-sided adhesive layer, the display module including, as one body:a main region including a display area disposed over the lower module,the main region having a first side end disposed in the first side area,the display area including an emissive unit having a first electrode, asecond electrode, and an emission layer between the first and secondelectrodes, the display area having a first side end disposed in thefirst side area; a sub region disposed under the lower module andoverlapping the main region, the sub region having a first side enddisposed in the first side area; and a bent region being disposed in thefirst side area and being between the first side end of the main regionand the first side end of the sub region such that the bent region isbent between the first side end of the main region and the first sideend of the sub region, the bent region having an outer surface betweenan upper surface of the main region and a lower surface of the subregion, and an inner surface between a lower surface of the main regionand an upper surface of the sub region; a functional module disposed onthe main region, the functional module having a first side end disposedin the first side area; and a window module disposed on the functionalmodule, the window module having a first side end disposed in the firstside area, wherein the display module includes a lower inorganicencapsulation structure and an upper encapsulation structure, theemissive unit being located between the lower inorganic encapsulationstructure and the upper encapsulation structure, both of the upperencapsulation structure and the window module are flexible, the firstside end of the main region is disposed outwardly away from the firstside end of the display area in plan view, and the first side end of themain region is not disposed inwardly away from the first side end of thelower module in plan view, the upper encapsulation structure has a lowersurface comprising only at least one inorganic material, the lowerinorganic encapsulation structure and the upper encapsulation structuredirectly contacting each other to encapsulate the emissive unit, thefoldable display device comprises a height-compensating layer structurehaving at least a portion disposed on the main region, disposedoutwardly away from the first side end of the functional module in planview, and disposed inwardly away from the first side end of the mainregion in plan view, the height-compensating layer structure has,between the main region and the window module, a height substantiallythe same as a distance between the main region and the window module,the height-compensating layer structure supports the window module,which is flexible, to prevent the window module from bending, theheight-compensating layer structure preventing an accumulation ofcontaminants near the first side end of the functional module, thefoldable display device comprises a bending protection layer disposed onthe outer surface of the bent region, the bending protection layer has afirst portion included in the at least the portion of theheight-compensating layer structure, and the first portion of thebending protection layer contacts the first side end of the functionalmodule.
 14. The foldable display device of claim 13, wherein theheight-compensating layer structure comprises an additional layer on thefirst portion of the bending protection layer.
 15. The foldable displaydevice of claim 13, wherein the functional module provides at least oneselected from the group of a polarization function, a color filteringfunction, a color conversion function, and a touch sensing function. 16.The foldable display device of claim 13, wherein the first side end ofthe functional module is disposed inwardly away from the first side endof the lower module in plan view, the lower module has a portiondisposed inwardly away from the first side end of the lower module inplan view and disposed outwardly away from the first side end of thefunctional module in plan view, a portion of the main region is disposedover the portion of the lower module to be supported by the portion ofthe lower module, and the at least the portion of theheight-compensating layer structure is disposed over the portion of themain region to be supported by the portion of the main region.
 17. Thefoldable display device of claim 13, wherein the foldable display devicecomprises: a base layer having first and second rigid plate portionsbetween which a foldable region of the foldable display device islocated, the base layer being disposed under the lower module; and acircuit board located under the base layer, and the sub region isdisposed between the base layer and the circuit board, the circuit boardbeing attached to the sub region such that the circuit board iselectrically connected to the sub region.
 18. The foldable displaydevice of claim 13, wherein the contaminants are carbon contaminantsgenerated when a laser ablation process is employed to form an outerperiphery of at least one selected from the group of the display moduleand the window module.
 19. A mobile terminal with a foldable displaydevice, the foldable display device providing an image displayed fromthe mobile terminal, wherein the improvement comprises that the foldabledisplay device comprises: a lower module having a first side enddisposed in a first side area of the foldable display device; adouble-sided adhesive layer on the lower module; a display module on thedouble-sided adhesive layer, the display module including, as one body:a main region including a display area disposed over the lower module,the main region having a first side end disposed in the first side area,the display area including an emissive unit having a first electrode, asecond electrode, and an emission layer between the first and secondelectrodes, the display area having a first side end disposed in thefirst side area; a sub region disposed under the lower module andoverlapping the main region, the sub region having a first side enddisposed in the first side area; and a bent region being disposed in thefirst side area and being between the first side end of the main regionand the first side end of the sub region such that the bent region isbent between the first side end of the main region and the first sideend of the sub region, the bent region having an outer surface betweenan upper surface of the main region and a lower surface of the subregion, and an inner surface between a lower surface of the main regionand an upper surface of the sub region; a functional module disposed onthe main region, the functional module having a first side end disposedin the first side area; and a window module disposed on the functionalmodule, the window module having a first side end disposed in the firstside area, wherein the display module includes a lower inorganicencapsulation structure and an upper encapsulation structure, theemissive unit being located between the lower inorganic encapsulationstructure and the upper encapsulation structure, both of the upperencapsulation structure and the window module are flexible, the firstside end of the main region is disposed outwardly away from the firstside end of the display area in plan view, and the first side end of themain region is not disposed inwardly away from the first side end of thelower module in plan view, the upper encapsulation structure has a lowersurface comprising only at least one inorganic material, the lowerinorganic encapsulation structure and the upper encapsulation structuredirectly contacting each other to encapsulate the emissive unit, thefoldable display device comprises a height-compensating layer structurehaving at least a portion disposed on the main region, disposedoutwardly away from the first side end of the functional module in planview, and disposed inwardly away from the first side end of the mainregion in plan view, the height-compensating layer structure has,between the main region and the window module, a height substantiallythe same as a distance between the main region and the window module,and the height-compensating layer structure supports the window module,which is flexible, to prevent the window module from bending, theheight-compensating layer structure preventing an accumulation ofcontaminants near the first side end of the functional module.
 20. Themobile terminal of claim 19, wherein the foldable display device has aspace between the height-compensating layer structure, the main region,and the first side end of the functional module, the space having aclosed shape in cross-sectional view.
 21. The mobile terminal of claim20, wherein the foldable display device comprises a bending protectionlayer disposed on the outer surface of the bent region, the bendingprotection layer has a first portion included in the at least theportion of the height-compensating layer structure, and the firstportion of the bending protection layer is spaced apart from the firstside end of the functional module.
 22. The mobile terminal of claim 21,wherein the height-compensating layer structure comprises an additionallayer on the first portion of the bending protection layer.
 23. Themobile terminal of claim 20, wherein the functional module provides atleast one selected from the group of a polarization function, a colorfiltering function, a color conversion function, and a touch sensingfunction.
 24. The mobile terminal of claim 20, wherein the first sideend of the functional module is disposed inwardly away from the firstside end of the lower module in plan view, the lower module has aportion disposed inwardly away from the first side end of the lowermodule in plan view and disposed outwardly away from the first side endof the functional module in plan view, a portion of the main region isdisposed over the portion of the lower module to be supported by theportion of the lower module, and the at least the portion of theheight-compensating layer structure is disposed over the portion of themain region to be supported by the portion of the main region.
 25. Themobile terminal of claim 20, wherein the contaminants are carboncontaminants generated when a laser ablation process is employed to forman outer periphery of at least one selected from the group of thedisplay module and the window module.
 26. The mobile terminal of claim20, wherein the foldable display device comprises: a base layer havingfirst and second rigid plate portions between which a foldable region ofthe foldable display device is located, the base layer being disposedunder the lower module; and a circuit board located under the baselayer, and the sub region is disposed between the base layer and thecircuit board, the circuit board being attached to the sub region suchthat the circuit board is electrically connected to the sub region. 27.The mobile terminal of claim 19, wherein the functional module providesat least one selected from the group of a polarization function, a colorfiltering function, a color conversion function, and a touch sensingfunction.
 28. The mobile terminal of claim 19, wherein the first sideend of the functional module is disposed inwardly away from the firstside end of the lower module in plan view, the lower module has aportion disposed inwardly away from the first side end of the lowermodule in plan view and disposed outwardly away from the first side endof the functional module in plan view, a portion of the main region isdisposed over the portion of the lower module to be supported by theportion of the lower module, and the at least the portion of theheight-compensating layer structure is disposed over the portion of themain region to be supported by the portion of the main region.
 29. Themobile terminal of claim 19, wherein the contaminants are carboncontaminants generated when a laser ablation process is employed to forman outer periphery of at least one selected from the group of thedisplay module and the window module.
 30. The mobile terminal of claim19, wherein the foldable display device comprises: a base layer havingfirst and second rigid plate portions between which a foldable region ofthe foldable display device is located, the base layer being disposedunder the lower module; and a circuit board located under the baselayer, and the sub region is disposed between the base layer and thecircuit board, the circuit board being attached to the sub region suchthat the circuit board is electrically connected to the sub region. 31.A mobile terminal with a foldable display device, the foldable displaydevice providing an image displayed from the mobile terminal, whereinthe improvement comprises that the foldable display device comprises: alower module having a first side end disposed in a first side area ofthe foldable display device; a double-sided adhesive layer on the lowermodule; a display module on the double-sided adhesive layer, the displaymodule including, as one body: a main region including a display areadisposed over the lower module, the main region having a first side enddisposed in the first side area, the display area including an emissiveunit having a first electrode, a second electrode, and an emission layerbetween the first and second electrodes, the display area having a firstside end disposed in the first side area; a sub region disposed underthe lower module and overlapping the main region, the sub region havinga first side end disposed in the first side area; and a bent regionbeing disposed in the first side area and being between the first sideend of the main region and the first side end of the sub region suchthat the bent region is bent between the first side end of the mainregion and the first side end of the sub region, the bent region havingan outer surface between an upper surface of the main region and a lowersurface of the sub region, and an inner surface between a lower surfaceof the main region and an upper surface of the sub region; a functionalmodule disposed on the main region, the functional module having a firstside end disposed in the first side area; and a window module disposedon the functional module, the window module having a first side enddisposed in the first side area, wherein the display module includes alower inorganic encapsulation structure and an upper encapsulationstructure, the emissive unit being located between the lower inorganicencapsulation structure and the upper encapsulation structure, both ofthe upper encapsulation structure and the window module are flexible,the first side end of the main region is disposed outwardly away fromthe first side end of the display area in plan view, and the first sideend of the main region is not disposed inwardly away from the first sideend of the lower module in plan view, the upper encapsulation structurehas a lower surface comprising only at least one inorganic material, thelower inorganic encapsulation structure and the upper encapsulationstructure directly contacting each other to encapsulate the emissiveunit, the foldable display device comprises a height-compensating layerstructure having at least a portion disposed on the main region,disposed outwardly away from the first side end of the functional modulein plan view, and disposed inwardly away from the first side end of themain region in plan view, the height-compensating layer structure has,between the main region and the window module, a height substantiallythe same as a distance between the main region and the window module,the height-compensating layer structure supports the window module,which is flexible, to prevent the window module from bending, theheight-compensating layer structure preventing an accumulation ofcontaminants near the first side end of the functional module, thefoldable display device comprises a bending protection layer disposed onthe outer surface of the bent region, the bending protection layer has afirst portion included in the at least the portion of theheight-compensating layer structure, and so the first portion of thebending protection layer contacts the first side end of the functionalmodule.
 32. The mobile terminal of claim 31, wherein theheight-compensating layer structure comprises an additional layer on thefirst portion of the bending protection layer.
 33. The mobile terminalof claim 31, wherein the functional module provides at least oneselected from the group of a polarization function, a color filteringfunction, a color conversion function, and a touch sensing function. 34.The mobile terminal of claim 31, wherein the first side end of thefunctional module is disposed inwardly away from the first side end ofthe lower module in plan view, the lower module has a portion disposedinwardly away from the first side end of the lower module in plan viewand disposed outwardly away from the first side end of the functionalmodule in plan view, a portion of the main region is disposed over theportion of the lower module to be supported by the portion of the lowermodule, and the at least the portion of the height-compensating layerstructure is disposed over the portion of the main region to besupported by the portion of the main region.
 35. The mobile terminal ofclaim 31, wherein the foldable display device comprises: a base layerhaving first and second rigid plate portions between which a foldableregion of the foldable display device is located, the base layer beingdisposed under the lower module; and a circuit board located under thebase layer, and the sub region is disposed between the base layer andthe circuit board, the circuit board being attached to the sub regionsuch that the circuit board is electrically connected to the sub region.36. The mobile terminal of claim 31, wherein the contaminants are carboncontaminants generated when a laser ablation process is employed to forman outer periphery of at least one selected from the group of thedisplay module and the window module.